A paper is in square form with a side 20cm. Two semicircles are drawn on its opposite sides as diameters. If these semicircles are cut down. the area (in sq.cm) of the remaining part of the paper is

A

$$400 - 200 \pi$$

B

$$400 - 100 \pi$$

C

$$400 - 50 \pi$$

D

$$400 - 80 \pi$$