If B5 receives a dropped third strike while R2 and R3 are on base, what determines whether he is safe or out?

When B5 receives a dropped third strike, his status as safe or out is contingent upon the actions of both the catcher and how B5 interacts with the base. If the catcher catches the pitch and holds onto the ball when B5 touches the base, it means the catcher has effectively made the play to retire the batter. Conversely, if the ball is not held and B5 reaches the base, he is safe. This rule emphasizes the necessity for the fielder (in this case, the catcher) to maintain control over the ball while B5 touches the base.

In this scenario, the correct determination of B5's status hinges upon the catcher’s possession of the ball at the moment B5 touches the base, making it clear why the option indicating that he is safe if the ball is held by the fielder is accurate. This reflects the rule's intent to create a clear distinction between running safely to the base and being out as a result of the catcher's action.