What should be done to determine if slack adjusters need adjustment?

Answer: B — Release both the service and parking brakes

To determine if slack adjusters need adjustment, releasing both the service and parking brakes is essential. When the brakes are released, this allows the slack adjusters to return to their resting position. By doing so, you can inspect the movement of the slack adjusters effectively. If they are adjusted properly, there shouldn't be any excessive play in the brake system. Knowing the correct state of the slack adjusters is critical for maintaining effective braking performance. Insufficient slack can lead to brakes remaining partially engaged, potentially causing overheating or increased wear, while excessive slack can create a significant distance before the brakes engage, leading to unsafe driving conditions. By ensuring that both sets of brakes are released, you can accurately assess whether adjustments are necessary to keep the braking system operating safely and properly.