There are essentially three rules in these sorts of power multiplication problems:
These rules just tell us a negative exponent means the reciprocal of the same thing with a positive exponent, that when we multiply factors with the same base we add their exponents, and when we raise something to a power to another power we get to multiply the exponents.
Let's do the algebra before we substitute (we could do it either way).
Substituting p=-2, q=-1
Answer: 4, last choice