If f(x) = (xm + 9)2, which statement about f(x) is true?

I would say none of these .

for x to be even then f(x) = f(-x) for all values of x in the domain.
Suppose x=1 and m=1 then f(x) = 20. f(-1) is 16 so f(x) does not equal f(-x)

for it to be odd then either f(x) = -f(x) or f(x) + f(-x) = 0 . Looking at teh above example neither is true.

That is an odd value of m . if you use m=2 you have exactly the same effect so its not even or odd for an even value of m.

So unless you've got a very restricted domain for the function none of these statements are true.