Technician a Says That the Steering Column Mounted,hand Control Valve

Technician A says that the steering column mounted,hand control valve actuates the tractor service brakes without applying the trailer brakes.Technician B says that the hand control valve sources its air from the tractor secondary circuit when functioning normally.Who is correct?

A) Technician A only
B) Technician B only
C) Both A and B
D) Neither A nor B