The highest common factor of the polynomials $$p(x) = x^4 - 2ax^3 - 3a^2x^2$$ and $$q(x) = x^5 - 2ax^4 - 8a^2x^3$$ is

A

$$x^2(x + a)$$

B

$$x^2(x - 3a)$$

C

$$x^2(x + 3a)$$

D

$$x^2$$