Geometry

The answer is D.

 

1. Recall the concept of a mid - point:

A mid - point of a line segment divides the segment into two congruent (equal - length) parts. So, if is the mid - point of , then .

 

2. Analyze each figure:

First figure: There are no markings to suggest that and are of equal length. So, we can't conclude that is the mid - point of .

 

Second figure: The tick marks indicate that and are equal, meaning is the mid - point of , not being the mid - point of .

 

Third figure: The order of points is ,