The breathing air system must provide air for at least how many persons at the secondary operator's position?

• A. Two
• B. Three
• C. Four
• D. One

Answer: (D)

The key idea is that the breathing air system at the secondary operator’s position is designed to support a single user. The secondary operator needs a dedicated air supply to perform tasks safely, without relying on or risking depletion of another line meant for someone else. Providing air for one person ensures there is enough flow and duration for the secondary operator to work effectively in that position. Supplying air for more than one person would require a larger, more complex system and isn’t the minimum requirement here, so the safest, simplest baseline is one.