Which of the following move the primary and secondary pistons back to their starting positions when the brake pedal is released? A) The fuid pressure in the compensating ports. B) The square-out caliper piston seals. C) The piston return springs. D) The brake shoe return springs.

## Step 1<br />The problem is about the braking system in vehicles. When the brake pedal is released, the primary and secondary pistons need to return to their original positions. This action is facilitated by the piston return springs.<br /><br />## Step 2<br />The other options, such as the fluid pressure in the compensating ports, the square-out caliper piston seals, and the brake shoe return springs, do not perform this function. The fluid pressure in the compensating ports is responsible for maintaining the pressure in the braking system. The square-out caliper piston seals prevent fluid leakage and ensure the smooth operation of the pistons. The brake shoe return springs are responsible for returning the brake shoes to their original position.