Answer:
c. Both Technicians A and B
Step-by-step explanation:
ABS stands for anti lock braking system. It prevents the vehicle to skid while braking action in slippery surfaces and prevents lockup of the wheels.
The ABS ban be bled using a bleeder screw. Bleeding the brake means removing the air inside for a firm brake pedal. Thus to remove the air, open the bleeder screw of the ABS and allow to pass the air out while turning on the engine.
A fully featured scan tool is required to fully bleed the air in the ABS system. The bi-directional control of the modulator can purge air bubbles out that can not be done with normal bleeding.
Thus both technician A and technician B are correct.