Let $$z_1$$ and $$z_2$$ be two complex numbers such that $$z_1 + z_2 = 5$$ and $$z_1^3 + z_2^3 = 20 + 15i$$. Then $$z_1^4 + z_2^4$$ equals

A

$$30\sqrt{3}$$

B

75

C

$$15\sqrt{15}$$

D

$$25\sqrt{3}$$