Answer: B is correct.

Explanation:
Given expression :

First we write expression into division form.

Change division to multiplication. Expression after division will flip and division sign change to multiply
----------- (A)
Formula:

-------------------------(B)
--------------------------(C)
Substitute B and C into A and we get,
Cancel like factor from top and bottom.
Cancel factors are m+3 and m+4 and we get,

B is correct.