Answer:
a) technician A
Explanation: A parking brake is a secondary and support brake system which is usually applied when the vehicle is not in motion,this is done to prevent any form of motion and the possibility of any form of accident.
A secondary circuit is a circuit or coil in which current is generated through induction from another circuit or coil called the primary circuit,it has not been discovered that a low pressure from that circuit has led to poor trailer parking brake performance.