When is a baserunner forced to advance?

• A. When the preceding runner is forced.
• B. When the ball crosses first base
• C. When the batter hits a foul ball
• D. When the umpire calls time

Answer: (A)

A baserunner is forced to advance when the runner ahead of them is forced to move. This is the essence of a force play: the batter becomes a runner and the defense could put him out at first, so the base behind the batter’s advance must be vacated. If the preceding runner is compelled to advance to the next base, the runner behind him must also move up to keep the base paths clear. The other situations listed don’t create a forced advance—crossing first base, a foul ball, or time being called stops or ends play but doesn’t compel a runner to move yet.