Which of the following best describes an acute angle?

An acute angle is defined as an angle that measures less than 90 degrees. This characteristic distinguishes acute angles from other types of angles. For instance, a right angle measures exactly 90 degrees, which does not meet the criteria for being acute. Similarly, angles that measure more than 90 degrees are classified as obtuse angles, while an angle that measures 180 degrees is called a straight angle. Therefore, the defining feature of acute angles is their measurement of less than 90 degrees, making the given answer correct. Understanding these distinctions is key in geometry, as they lay the foundation for more complex angle relationships.