A

Step 1: Analyze the Assertion. The displacement of a body is defined as the shortest straight-line distance from its initial position to its final position. This means that it is possible for the displacement to be zero if the body returns to its starting point, even if it traveled a considerable distance in between. Therefore, the assertion is true.
Step 2: Analyze the Reason. The reason provided states that displacement is the longest distance between initial and final positions. However, this is incorrect; displacement is, in fact, the shortest distance. Therefore, the reason is false.
Step 3: Evaluate the options. Since the assertion is true and the reason is false, the correct answer is C.