Answer:
C) x²-2x-15=0
Explanation:
You could put both -3 and 5 in the equations to guess and check, but the better way is to use them to create the factors. If -3 is a root, one of the factors must be (x+3). If 5 is a root, the other factor must be (x-5).
(x+3)(x-5)
x²-5x+3x-15=0
x²-2x-15=0