Which of the following are the three main types of angles?

The three main types of angles are acute, right, and obtuse, which makes this answer correct.

An acute angle is one that measures less than 90 degrees, a right angle measures exactly 90 degrees, and an obtuse angle is greater than 90 degrees but less than 180 degrees. These classifications primarily focus on the degree measures of angles and are fundamental concepts in geometry. Understanding these types of angles is crucial as they serve as the foundation for more complex geometric concepts and relationships.

The other combinations listed do not accurately represent the three main types of angles. For instance, the first option includes reflex angles, which are those greater than 180 degrees and are not one of the main classifications typically taught first. The final two choices introduce terms like complementary angles, which refer to a relationship between two angles that sum to 90 degrees rather than a type of angle itself.