Given:
\[
g(x) = p(x) = qx^n
\]
Assume \( n \) is even (since question implies extremum), and \( p>0 \), \( q>0 \)
Then \( g(x) = qx^n \) is a parabola upwards, so has minimum at \( x = 0 \)
\[
g(0) = 0, \text{and } g(x)>0 \text{ for all } x \neq 0
\Rightarrow \boxed{\text{Minimum at } x = 0}
\]
Final Answer: (c) Minimum when \( p>0, q>0 \)