The following figure represents two biconvex lenses $$L_1$$ and $$L_2$$ having focal length $$10 \text{ cm}$$ and $$15 \text{ cm}$$ respectively. The distance between $$L_1$$ & $$L_2$$ is 

A

$$10 \text{ cm}$$

B

$$35 \text{ cm}$$

C

$$25 \text{ cm}$$

D

$$15 \text{ cm}$$