Which of the following is considered obstruction in baseball?

Obstruction in baseball occurs when a defensive player prevents a runner from advancing by not allowing them to proceed along their base path. The correct answer involves a fielder simulating a tag on a runner without the ball, which is a deliberate act meant to mislead the runner. This action creates an unfair situation where the runner might hesitate or change their running path, thereby impacting their ability to advance safely.

In the context of the other options, they do not constitute obstruction in the same way. A fielder without the ball tagging a runner does not represent an obstruction situation if the runner is legally tagged. If a fielder with the ball blocks a runner's path, it can lead to obstruction, but it needs to be assessed that the fielder is intentionally impeding the runner's movement without making a legitimate attempt to play the ball. Meanwhile, a coach interfering with a play presents a separate issue of interference rather than obstruction since it involves a coach's actions affecting play rather than a fielder's position or actions while the ball is in play.