Question

Angles that are congruent and supplementary must be

A. acute angles.
B. obtuse angles.
C. straight angles.
D. right angles.

Answer 1

I think angles that are congruent and supplementary must be right angles because supplementary angles add up to 180 degrees. 

congruent angles have the same angle so 180/2 is 90 which is a right angle.

Answer 2

D. Right angles

In order to be supplementary, two angles must meet the sum of 180 degrees. In order to be congruent, two angles must be equal in measure.

90+90= 180

Hope this helps!