A simple pendulum, with a bob of mass $$m$$, oscillates in a vertical plane, with an angular amplitude $$\theta_0$$. The tension in its string when it passes through the mean position is $$2mg$$. Neglecting the effect of air friction and the viscosity of air, the angular amplitude $$\theta_0$$ is

A

$$30^\circ$$

B

$$60^\circ$$

C

$$90^\circ$$

D

$$120^\circ$$