The answer is A.
1. Recall the definition of a mid - point:
A mid - point of a line segment divides the segment into two equal parts. That is, if is the mid - point of segment , then .
2. Analyze each figure:
First figure: The tick marks show that the distance from to is equal to the distance from to . So, divides segment into two equal parts, and is the mid - point of .
Second figure: The tick marks indicate that and are equal, which means is the mid - point of , not being the mid - point of