From a group of three boys and four girls, a school hallway monitor gr

I don't want to be rude but I did not understand whether positions are considered unique or not, anyway I'll answer in both cases:

In case positions are identical:
we need to form a group of 5 people in which 4 of them has to be girls. we already have 4 girls so no arranging here (only 1 option for arranging). we do have 3 boys and only 1 spot for 1 boy, so 3 options for the boys - so we can form 3 groups (each group has different boy)

Answer is B;

In case positions are unique:
let's start with the girls. let's assume that there are only 4 spots. the options for arranging the girls in those 4 spots are:
4! = 1*2*3*4 = 24
now, let's add the 5th spot. in every arrangement there will be 1 "Free" spot (not really free because one of the boys will sit there), so we can have 5 different options for free spot, therefore:
24*5=120

let's go back to the boys. remember the "free" spots? for every option with the "Free" sit, we can put 3 different boys to sit, and so the answer:
120*3 = 360

Answer is E;

Waiting the OA