The correct answer is A.
In order to find the correct answer in this one, you have to group all of the like terms. In this case, each term is unique with the exception of the x^2y^3 terms. Therefore, we need to check those first.
4x^2y^3 - (-5x^2y^3)
4x^2y^3 + 5x^2y^3
9x^2y^3
Since this term is included, we look for answers that involve this one. A is the only one that does. Plus, it includes each other term unchanged (which is good since there are no other like terms). Therefore, A is your answer.