B is the correct. Because if you look at the problem I can turn it around and see
42 / 38x
This sentence is just to fill up space.
5 can also be written as 5/1
knowing that each bottle is equal and is 3/4 full, multiply 5 by 3/4
5/1 x 3/4 will give you your answer.
remember just multiply straight across and simplify.