Final answer:
The finding from other research that would question the conclusion reported in the passage is that musicians usually perform more skillfully when a friend is present than when they are alone.
Step-by-step explanation:
The finding from other research that would be most apt to raise questions about the conclusion reported in the passage is option B: Musicians usually perform more skillfully when a friend is present than when they are alone. While the passage focuses on the impact of an audience on actors in live theatre, the research finding about musicians performing better when a friend is present raises questions about whether the presence of an audience is truly essential for enhanced performance. If musicians can perform better with just a friend present, it suggests that the presence of an audience may not be the only factor that influences performance. Additionally, the finding about musicians performing better with a friend present does not directly align with the conclusion reported in the passage, which specifically discusses the impact of an audience on actors in live theatre.