If the slant height of a cone is 60 cm and the radius of its base is 21 cm, then find its curved surface area.
[Use $$\pi = \frac{22}{7}$$]

A

3880 $$cm^{2}$$

B

3820 $$cm^{2}$$

C

3960 $$cm^{2}$$

D

4020 $$cm^{2}$$