The impedance of a series RLC circuit is

A

$$\sqrt{R^{2}+X_{l}^{2}+X_{c}^{2}}$$

B

$$\sqrt{R^{2}+X_{l}^{2}-X_{c}^{2}}$$

C

$$\sqrt{R^{2}+(X_{l}+X_{c})^{2}}$$

D

$$\sqrt{R^{2}+(X_{l}-X_{c})^{2}}$$