There are two main problems with the original sentence:
(1) The government authorities urged citizens to do three things: remain vigilant, report suspicious behavior, and take actions to speed up the recovery from an economic catastrophe. Consequently, these three requests from the government need to be parallel. In this case, each command should be in the infinitive form (e.g., to remain, to report, andto take). The original sentence wrongly constructs the phrase taking actions necessary to speed up the recovery from an economic catastrophe such that it modifies the two previous actions. Instead, this phrase should reflect the fact that taking actions... is a third action that the government is urging citizens to take. In short, the three actions that the government is urging are not parallel and they should be.
(2) taking actions necessary... illogically modifies the command to remain vigilant and report suspicious behavior because these two actions would not speed up the recovery from an economic catastrophe. In other words, it does not make sense that remaining vigilant and reporting suspicious behavior (two actions that would occur before an attack) would be modified such that these are actions that speed up the recovery from an attack.
A. The three actions that the government urged are not parallel (i.e., to remain is not parallel with taking); the word necessary is not needed
B. The three actions that the government urged are not parallel (i.e., to remain is not parallel with reporting and take)
C. The three actions that the government urged are not parallel (i.e., to remain is not parallel with reporting and taking); the word necessary is not needed
D. The sentence is correctly constructed as the three actions that the government urged are parallel; the un-needed word necessary is omitted
E. The meaning of the original sentence is distorted as this sentence indicates that the government asked citizens to be more vigilant in reporting suspicious behavior (a single command) while the original sentence separated the command to remain vigilant and the command to report suspicious behavior; the three actions that the government urged are not parallel

The conditional clause (the "if" clause) does not require would. Also we should write "inthe garden" to be parallel to "in the greenhouse".

The verb claims should be followed by one of two patterns: (1) that followed by a subordinate clause (2) claims followed by an infinitive (set apart by commas).
A. claims is correctly followed by that and a subordinate clause set apart by commas
B. the phrase claims of the ability, ..., of returning is neither grammatical nor idiomatic
C. the phrase claims of being able to return, ..., the investment is neither grammatical nor idiomatic
D. the phrase to be...able to return should not be split up as it creates an awkward construction; to be able to return can be made concise by removing to be able
E. the phrase returning the investment bank back is redundant as the words returningand back convey the same idea; the phrase he is capable of can be shortened to the phrase he can

There are two main issues being tested in this sentence.
(1) When using like or unlike, you must compare like parts (e.g., compare arguments with arguments). The original sentence improperly compares the team of lawyers with the government's argument.
(2) The expression, which modifies the term that is immediately before it. For example, the phrase the argument from the petitioner, which rested on a questionable interpretation of a bill that only recently passed Congress is incorrect since it was not the petitioner that rested on a questionable interpretation, but rather the argument that rested on a questionable interpretation.
A. the sentence illogically and improperly compares unlike parts (i.e., it compares the team of lawyers with the government's argument)
B. the phrase the argument from the petitioner, which rested on a questionable interpretation of a bill that only recently passed Congress is incorrect since it was not the petitioner that rested on a questionable interpretation, but rather the argument that rested on a questionable interpretation
C. the sentence properly compares like parts (i.e., it compares the petitioner's argument with the government's argument); , which rested on... properly and logically modifies the phrase it follows
D. the phrase whose case rested on is illogical since whose (which should modify a person) is actually modifying an argument
E. the original sentence, which reads a bill that only recently passed Congress, is perniciously changed to a new sentence, which reads a bill that recently only passed Congress; the difference in meaning between a bill that recently only passed Congress (meaning it did not become law) and a bill that only recently passed Congress (meaning it passed Congress a short time ago) is significant

The word which does not have an antecedent noun, and so the construction is incorrect in A and B. Similarly, in C this does not have a noun to which it refers. D is the best choice. In E the phrase emerging from the soil is dangling.