Assertion: A body can have an acceleration even if its velocity is zero at a given instant of time.
Reason: A body is momentarily at rest when it reverses its direction of motion.

The correct option is A If both Assertion and Reason are true and the Reason is correct explanation of the Assertion
Suppose velocity of a body and acceleration are in opposite direction, then surely acceleration acting in the opposite direction will slow down the velocity of the body. Ultimately, the body will momentarily come to rest before reversing its direction but at this instant of time only velocity will be zero and acceleration will still be acting on the body. So, the reason is the correct explanation of the assertion.