Answer: Choice D
Fold the paper so that A is on top of B
Or vice versa
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Step-by-step explanation:
M is the midpoint of segment AB.
This means that segments AM and MB are the same length, by definition of what it means to be a midpoint.
We have symmetry going on about point M. When we fold the paper, we're introducing symmetry. Point M will be on the folding line, and the folding line is the perpendicular bisector of AB.
It might help to use dark/heavy ink so that you can see the points on either side of the paper.