Sheila drew the diagram below.

Based on the diagram, which statement is true?
a The sum of the measures of the interior and exterior angles of a triangle is always 180°.
b The measure of an exterior angle of a triangle, angle C, is equal to the sum of the measures of the two non-adjacent interior angles of the triangle, angle A and angle B.
c The sum of the measures of the interior and exterior angles of a triangle is always 360°.
d The measure of an exterior angle of a triangle, angle C, is less than the sum of the measures of the two non-adjacent interior angles of the triangle, angle A and angle B.