Assertion: `x-t` graph, for a particle undergoing rectilinear motion, can be as shown in the figure.
Reason: Infinitesimal changes in velocity are physically possible only in infinitesimal time.
A. If both assertion and reason are true and reason is the correct explanation of assertion.
B. If both assertion and reason are true but reason is not the correct explanation of assertion.
C. If assertion is true but reason is false.
D. If assersion is false but reason is true.