In each part, determine all values of $p$ for which the integral is improper. Enter in interval notation or "none" if there are no relevant values of $p$.

(a) $\displaystyle \int_{0}^{5} \frac{dx}{x^{p}}$
$p$ values that make integral improper

(b) $\displaystyle \int_{0}^{4} \frac{dx}{x-p}$
$p$ values that make integral improper

(c) $\displaystyle \int_{9}^{10} e^{-px}dx$
$p$ values that make integral improper