What must happen for an ejected coach to return to the field?

For an ejected coach to return to the field, it is necessary for only the umpire to permit it. This is because the ejection of a coach is a serious disciplinary action taken to ensure fair play and maintain the integrity of the game. Once a coach has been ejected, they lose their right to be involved in any activities related to the game, and their return is strictly controlled. The umpire has the authority to enforce rules and can decide if and when an ejected coach may return, based on the circumstances and the necessity to ensure the game is conducted properly.

The other options do not reflect the established protocol regarding ejections. A request from the team does not override the umpire's authority; merely being on the field before an injury does not negate the ejection; and the notion that there are no conditions for return disregards the necessary involvement of the umpire in managing the game’s conduct.