Answer:
Reduce high-pressure gas in the scuba cylinder to ambient (surrounding) pressure.
Step-by-step explanation:
The primary function of a scuba regulator would be to reduce high-pressure gas in the scuba cylinder to ambient pressure.
A scuba regulator is a structure found attached to the scuba cylinder usually carried by scuba divers. The structure regulates the pressure of the breathing gas in the cylinder to a safe level before the gas becomes available for the breathing process of divers.
Usually, the gas in a scuba cylinder is at a high level. Hence, what the regulator does is to bring it down to a level that would be safe for the breathing of the diver.