One characteristic of a synchronous motor is that it operates at what type of speed?

A synchronous motor is defined by its ability to operate at a constant speed, which is directly tied to the supply frequency. This characteristic means that regardless of variations in load, a synchronous motor maintains its speed as long as it is in operation and properly synchronized.

The constant speed operation of synchronous motors is fundamental to their design and function, allowing them to be effectively used in applications where precise speed control is necessary, such as in robotics and conveyor systems. This feature is a key advantage over other types of motors, particularly induction motors, which can experience speed variations due to load changes.

While the other options describe certain characteristics or behaviors of motors, they do not encapsulate the primary defining characteristic of synchronous motors like constant speed does. Hence, the answer that highlights the constant speed operation is the most accurate in this context.