Which device creates rotary motion when current flows through it?

A motor is specifically designed to convert electrical energy into mechanical energy, producing rotary motion as a result. When current flows through the motor's coils, it generates a magnetic field that interacts with magnets or other magnetic materials, causing the rotor to spin. This rotary motion can then be harnessed for various applications, such as driving machinery or propelling vehicles.

In contrast, generators function by converting mechanical energy into electrical energy, which is the opposite process. Actuators can create rotary or linear motion, but they often operate based on different principles and may not specifically create rotary motion as their primary function. Solenoids, while they do convert electrical energy into motion, typically produce linear movement rather than rotary motion. Thus, the distinctive role of a motor in generating rotary motion when current flows through it makes it the correct choice for this question.