Two coils of self inductance $$L_1$$ and $$L_2$$ are connected in series combination having mutual inductance of the coils as $$M$$. The equivalent self inductance of the combination will be

A

$$\frac{1}{L_1} + \frac{1}{L_2} + \frac{1}{M}$$

B

$$L_1 + L_2 - 2M$$

C

$$L_1 + L_2 + M$$

D

$$L_1 + L_2 + 2M$$