Which one of the following represents displacement-time graph of two objects $A$ and $B$ moving with

Question

Which one of the following represents displacement-time graph of two objects $A$ and $B$ moving with zero relative velocity?

Professor PC Thomas Classes · Answer

(b): When velocity of $A=$ velocity of $B$, then, relative velocity is zero. ∴ Displacement-time graphs of $A$ and $B$ must have same slope (other than zero).