Two springs of of stiffness $$k_1$$ and $$k_2$$ respectively are connected in series, what will be the stiffness of the composite spring?

A

$$k = \frac{k_1k_2}{k_1 + k_2}$$

B

$$k = \frac{k_1 + k_2}{k_1k_2}$$

C

$$k = k_1 + k_2$$

D

$$k = k_1k_2$$