The given figure shows a particle moving along a curve ABCD.

Assertion (A) : The path followed by the particle is ABCD.

   Reason (R) : If we add the successive positions of the particle, we get the path of the particle

From the figure

   We can claim that Assertion is true that path of particles is along curve ABCD because we get    path of a particle by tracing the successive positions of the particle which is in motion.

      Here both Assertion (A) and Reason (R) are true and (R) is the correct explanation of (A).