What does it indicate when the official awards a one and one after a common foul?

When an official awards a one-and-one free throw opportunity after a common foul, it signifies that Team B has exceeded the limit of fouls allowed for that period, placing Team A in a bonus situation. In basketball, teams are penalized for committing a specific number of fouls within a half or quarter. When the foul count for Team B reaches that threshold—usually seven team fouls in a half—any subsequent fouls committed by that team will allow the opposing team to shoot free throws under the one-and-one rule.

This rule means that the player attempting the free throw will shoot one free throw, and if they make it, they are awarded a second attempt. Thus, awarding the one-and-one indicates the rules are activated because of the cumulative fouls committed by Team B, leading to an advantage for Team A in terms of scoring opportunity at the free-throw line.

The other choices do not accurately represent the situation: awarding a one-and-one does not indicate an immediate advantage to Team A outside of the free throw context, does not imply that substitutions are required, and while it might relate to Team B's fouling behavior, the direct implication is more specifically about Team A's bonus status.