Answer:
C. He found the midpoint of a segment.
Step-by-step explanation:
The midpoint is the point that divides a segment into two equal parts. Thus it is located at the middle of the segment.
John used this simple method to determine the midpoint of a segment. For example, let a segment AB = 10 cm be folded in half. A point made at the fold would be at 5 cm, which is the midpoint of the segment.
Thus the appropriate answer to the question is option C.