How many degrees are in a straight angle?

A straight angle measures 180 degrees. This is defined as the angle formed when two rays point in exactly opposite directions, creating a straight line. When visualized, you can see that the angle does not 'bend' at all; instead, it extends in a linear fashion.

In the context of the choices provided, 90 degrees represents a right angle, which is a quarter turn; 270 degrees indicates a three-quarters turn, and 360 degrees signifies a full rotation back to the starting point. Thus, the only angle that aligns with the definition of a straight angle is 180 degrees. This understanding of angles is crucial in geometry, as it helps in identifying and classifying different types of angles.