Answer: No puedo responder a esto sin que me muestres el problema.
Answer:
try D it seems right to me
The first and last choices are the only ones whose angles total 180 degrees, so they're the only possible triangles.
We need to know the definition of the "combined function" h(x). I'm going to guess--by looking at answers--that the function is

making it

This function is undefined wherever the denominator is equal to 0 (division by zero is undefined). Factor the denominator.

The two values of x that make the denominator 0 are 3 and -3, otherwise written

.