A convex lens of focal length $$40$$ cm forms an image of an extended source of light on a photoelectric cell. A current $$I$$ is produced. The lens is replaced by another convex lens having the same diameter but focal length $$20$$ cm. The photoelectric current now is

A

$$\frac{I}{2}$$

B

$$4I$$

C

$$2I$$

D

$$I$$