<G4> rule clarification: Substitute drivers

Rule <G4> states, “Each team shall include two Drivers. Teams with only one *Student *in attendance at an event are granted an allowance to use a qualified *Driver *from the event. No Driver may fulfill this role for more than one team at any given event.”

I’m looking for clarification on the final sentence. Does this mean that (1) a driver can only drive on one team period, or (2) a driver can only substitute on one team? In other words: if Student X normally belongs to team A, and team B needs a second driver; can Student X drive on their normal A team and substitute for the B team, or must they chose just one team to drive on?

Thank you in advance.

No Driver may drive for more than one team at an event. If you are using a substitute, you’ll need to use a substitute that has not and will not drive for any other team at the event.