If AB is bisected by M and the length of AB is 12, then A must be 6 units away from M.
It's parallel to the x-axis, so only worry about x-coords for now.
-2 is 10 away from -12.
-2 is 8 away from -10
-2 is 6 away from 4
-2 is 6 away from -8
However, -8 makes more sense because it should go A, then M, then B. So the answer is C. (-8,5)