$$\triangle ABC \sim \triangle PQR$$. The areas of $$\triangle ABC$$ and $$\triangle PQR$$ are 64 cm$$^2$$ and 81 cm$$^2$$, respectively and AD and PT are the medians of $$\triangle ABC$$ and $$\triangle PQR$$, respectively. If PT = 10.8 cm, then AD =?

A

8.4 cm

B

9 cm

C

9.6 cm

D

12 cm