Maria looked at the sketch of a section of roof shown below.
100°
40°
She said that y must be 40°. Which statement justifies Maria's conclusion?
O A triangle has two congruent angles.
O An obtuse triangle has one obtuse angle and two acute angles.
O The sum of the measures of the angles of a triangle is 180°.
O The measure of an exterior angle equals the sum of the measures of its two remote interior angles.