The answer is D, because the question asks for "...the sum of x and 5..." which means that they want x and 5 to be together, so that eliminates every answer choice except D.
Sixteen -------> 16 divided by -------> / the sum of x and 5 -----> x+5 is 12 ------> = 12
16/x+5 = 12
Answer D
The reason it is NOT answer A is because is says "divided by the sum of x and 5". In the order of operations, division happens before addition, so if it did not say "the sum of", then 16 divided by x (16/x) would happen before adding 5 (like in answer A). But is says "the sum of" so you have to do the addition first.
