A $2-$kg ball dropped vertically undergoes an inelastic collision with a horizontal floor and bounces up$.$ The instant before it hits the floor, the speed of the ball is $2\frac{m}{s}.$ The instant after the bounce, the speed of the ball is $1\frac{m}{s}.$ The change in the momentum of the ball is:

A$)2$ N$.$s$,$ Up

B$)2$ N$.$s$,$ Down

C$)6N.s,Up$

D$)6$ N$.$s$,$ Down

E$)$ zero