Two coils wound on the same magnetic core have inductances $$L_1$$ and $$L_2$$. When the two coils are connected in series, the effective inductance is

A

$$L_1 + L_2$$.

B

certainly greater than $$L_1 + L_2$$.

C

certainly less than $$L_1 + L_2$$.

D

none of the above.