What signifies a minor defect in the hydraulic brake system?

The identification of a minor defect in the hydraulic brake system is accurately represented by the fluid level being below the minimum level mark. In hydraulic brake systems, the brake fluid is crucial for transmitting force from the brake pedal to the brake components. When the fluid level is below the minimum mark, it can indicate a leak in the system or worn brake pads, leading to air entering the system or inadequate fluid to create the necessary hydraulic pressure. While this situation is serious and requires attention, it is classified as a minor defect as opposed to complete brake failure.

In contrast, other options present situations that may suggest issues, but they do not directly identify a minor defect in the hydraulic brake system. For example, having the fluid level above the minimum mark indicates that the system has sufficient brake fluid. Wearing down brake pads can indeed affect braking efficiency but is typically considered a maintenance issue rather than a defect within the hydraulic system itself. Similarly, malfunctioning brake lights relate to electrical aspects of the vehicle and do not reflect the functioning of the hydraulic brake system.