Which of the following applies to three-phase motors?

Three-phase motors can be connected in different configurations, with the most common being delta and wye (also referred to as star). Each configuration has its advantages and provides different voltage and current characteristics. A delta connection typically allows for higher current and is used in applications that require more power, while a wye connection is more efficient for supplying higher voltage with lower current. The ability to choose between these two configurations based on system requirements is what makes option B correct.

Other options present limitations or inaccuracies about the nature of three-phase motors. While some motors can operate at a single voltage, three-phase motors commonly can handle multiple voltage levels depending on their connection type. The option stating that they can only be star-connected is incorrect, as they can indeed be delta-connected as well. The requirement for a starting capacitor generally applies to single-phase motors rather than three-phase motors, which typically do not need additional starting assistance due to their design and the nature of three-phase power.