Which of the following is true for displacement? 

The displacement between two places A and B, which may or may not be the same position, is the length of the shortest straight line path between them.
The shortest straight line path between two places A and B, which may or may not be the same, is referred to as displacement.
In contrast, distance describes the length of the actual journey a body takes to get from point A to point B.
If the body moves along a curved path from point A to point B, the length of the path it travels will be greater than the length of the straight line connecting points A and B. (which is in fact, the displacement).

As a result, when a body moves from one point to another, the amplitude of its displacement can never be more than the distance it travels. Only if the body travels in a direct straight line between the two places can the displacement and distance traveled directlydirectly by the body be identical.

The displacement will be 0 if the two points A and B are the same since the shortest distance between them is really a zero point. The distance, however, might not be zero since the body might go from point A to point C and then return from point C to point B (which in this case is the same as point A), where C is another point. Consequently, the real length of the body's route (the distance) is not zero.
As a result, whereas distance can never be 0, displacement can if the beginning and finishing positions are the same.

Hence, the correct option is C.