If the brakes of a car tend to drag, which component could be the problem?

The presence of dragging brakes is typically attributed to a mechanical issue within the braking system. A stuck wheel cylinder or caliper piston can lead to the brake pads or shoes continuously making contact with the brake rotor or drum, which causes friction and heat. This persistent contact is what results in the dragging sensation when the car is in motion.

When investigating issues with brake drag, it's crucial to consider that a properly functioning wheel cylinder or caliper piston should allow for the smooth operation of the brake components, enabling them to disengage fully when the brakes are not applied. In contrast, a stuck component fails to retract as designed, leading to the situation where brakes do not release properly.

Other factors, such as a loose brake line or an air bubble in brake fluid, are generally associated with different types of braking problems, like reduced brake efficiency or spongy brake feel rather than dragging. A malfunctioning brake light switch affects the electrical system related to the brake indicator lights but does not directly impact the mechanical operation of the brakes. Hence, given the scenario, the issue of dragging brakes can most accurately be associated with a stuck wheel cylinder or caliper piston.