The Refrigerant from a Vehicles A/C System Is Being Recovered

Multiple Choice

The refrigerant from a vehicles A/C system is being recovered into a recovery unit.Technician A says that both the vapor and liquid tank valves on the recovery unit should be OPEN.Technician B says that both the high-side and low-side gauge valves on the manifold and gauge set should be OPEN.Who is correct?

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