What is the sum of complementary angles?

Complementary angles are defined as two angles whose measures add up to 90 degrees. This relationship arises from their specific geometric properties and is a fundamental principle in the study of angles within Euclidean geometry. When two angles are created, such as when a line intersects another, these angles can be categorized based on their measures. If their combined measure equals 90 degrees, they are considered complementary.

In this case, since the definition of complementary angles directly states that their sum equals 90 degrees, the correct choice aligns perfectly with this established concept. Recognizing this helps to clarify any misconceptions about the relationships between different types of angles, satisfying the requirement of the question posed.