They have asked for double the number of boys originally present
When we double a whole number, it will always be even number.
So 125 and 93 cannot be options.
Now we are left with 160 and none of the above.
Take 160 first and check for conditions.
160 = double the original number of boys.
Original number of boys = 160/2 = 80
When 30 boys leave, 50 boys are left and there are 4 girls for each boy
So number of girls = 4 × 50 = 200
When 175 girls leave, 25 girls are left and there will be 2 boys for each
girl as number of boys are 50
So conditions satisfied.
Double the number of boys originally present = 160