Answer: Choice C
Step-by-step explanation
If x = 5 is a root of Q(x), then x-5 is a factor of Q(x).
Since x-5 is a factor, it means:
Q(x) = (x-5)*P(x)
Replacing x with 5 will get us the following
Q(x) = (x-5)*P(x)
Q(5) = (5-5)*P(5)
Q(5) = 0*P(5)
Q(5) = 0
We don't need to worry about what P(5) is equal to, since it cancels with the 0. The only thing known about P(x) is that it's some quadratic.