One sign of a defective hydraulic brake system is __________.

• A. Low gas mileage
• B. Uneven tire wear
• C. Non-operational stop lights
• D. Low brake fluid level

Answer: (D)

In a hydraulic brake system, braking power comes from fluid pressure that moves from the master cylinder through the lines to the brakes. If the fluid level is low, there isn’t enough fluid to create proper pressure, which weakens braking performance and can point to leaks or worn components in the system. That direct link to the hydraulic mechanism makes a low brake fluid level the clear sign of a hydraulic brake problem.

The other options don’t fit as direct indicators of a hydraulic issue: low gas mileage relates to the engine and drivetrain, uneven tire wear can be caused by alignment or suspension problems, and non-operational stop lights point to electrical or switch issues rather than the hydraulic system.