Which of the following can cause a brake system to lose pressure?

Losing pressure in a brake system can significantly hinder vehicle performance and safety. A leak in the brake lines is a critical factor that directly leads to a decrease in hydraulic pressure within the brake system. The braking system relies on hydraulics to function effectively, meaning that when there is a leak—whether from a worn-out line, a damaged connector, or a seal failure—the fluid pressure is compromised, leading to reduced braking efficiency or complete brake failure.

In contrast, while a faulty brake light or dirty brake pads may lead to other issues within the vehicle, they do not influence hydraulic pressure within the brake system directly. Low tire pressure affects vehicle traction and handling but does not impact the brake fluid's hydraulic system. Each component plays a role in vehicle safety, but only a leak in the brake lines can directly impair the ability to maintain proper brake system pressure.