What is one time when a scrum master participates but does not necessarily facilitate?

a. during team breakout sessions at pi planning
b. if the entire team is present during the daily stand-up
c. when using ad-hoc teams for inspect and adapt
d. when the agile release train does not require any team coordination

C. when using ad-hoc teams for inspect and adapt

Explanation:

The purpose of a scrum master in a social situation is to somehow make all the participants solve a problem by their own capabilities. So , it is important for Scrum master to participates as little as possible.

But, there is an exception.

Sometimes, Scrum master will participate During inspection and adaptation process. When given independence to solve problems by their own, the chance of making a mistake is pretty high. This is why Scrum master will participate during inspection and adaptation process, to ensure that the end result will always right.