The correct option is D vB=vC=vD
Given velocity at point B,C,D is vB,vC and vD respectively
Since, total mechanical energy is constant
PEi+KEi=PEf+KEf
Here, Initial point is A and final points are B,C,D
Ball have only potential energy at point A and kinetic energy at point B,C,D
v=√2gh, where h is the vertical height from initial point to final point
So change in velocity depends only on height difference.
As height is same for all, vB=vC=vD