How many degrees are in a right angle?

A right angle is defined as an angle that measures exactly 90 degrees. This fundamental concept in geometry is crucial, as right angles are used to define perpendicular lines and are a key component in various geometric shapes, such as squares and rectangles. Recognizing that a right angle measures 90 degrees allows one to understand relationships between other angles, particularly complementary angles, which sum to 90 degrees. Therefore, the correct answer directly follows from the established geometric definition of a right angle.