A bullet of mass 10g moving horizontally with a velocity of $$400 ms^{-1}$$ strikes a wooden block of mass 2 kg which is suspended by a light inextensible string of length 5 m. As a result, the centre of gravity of the block is found to rise a vertical distance of 10 cm. The speed of the bullet after it emerges out horizontally from the block will be

A

$$80ms^{-1}$$

B

$$120ms^{-1}$$

C

$$160ms^{-1}$$

D

$$100ms^{-1}$$