Answer:
only line r
Explanation:
the question is what is perpendicular to (has an angle of 90 degrees with) AM.
line r is.
line s has no right angle with AM (even the extended line beyond these points).
MB is parallel to AM. in fact it is on the same line. so, they have 0 degrees and not 90.
JK is just a part of line s, and the same as for line s applies.