If the diameter and height of a cylinder are d cm and $$\frac{d}{2}$$ cm, respectively, then its volume is:

A

$$\pi \frac{d^2}{4}$$ cm$$^3$$

B

$$\pi d^2$$ cm$$^3$$

C

$$\pi \frac{d^2}{2}$$ cm$$^3$$

D

$$\pi \frac{d^3}{8}$$ cm$$^3$$