Answer:
For the first one:
D) The perpendicular bisector of line MN
For the second one:
You need a protractor (angle ruler) to measure the angle. After finding the measurement, divide it into two. After finding the result, find the point that has that angle.
Example -
The pie measures 120°.
120° ÷ 2 = 60°
Find the point that measures 60° and connect the points (from the start to the edge of the pie).
For the third one:
C) m∠ABD ≅ m∠CBD