A uniformly charged thin spherical shell of radius R carries uniform surface charge density of $$\sigma$$ per unit area. It is made of two hemispherical shells, held together by pressing them with force F (see figure). F is proportional to

A

$$\frac{1}{ε_0}\sigma^2 R^2$$

B

$$\frac{1}{ε_0}\sigma^2 R$$

C

$$\frac{1}{ε_0}\frac{\sigma^2}{R}$$

D

$$\frac{1}{ε_0}\frac{\sigma^2}{R^2}$$