To determine which option could threaten the effectiveness of the panel, let's analyze each option:
A. Mark can't make it to the meetings and has to contribute by telephone.
- This could potentially hinder effective communication and collaboration during the meetings, but it may not be a decisive factor if he can still contribute meaningfully.
B. Jim gets mad at the rest of the panel, turns in his diary, and quits the panel.
- This is a significant issue as it affects group cohesion, morale, and the overall dynamics of the panel. Losing a member can disrupt the continuity and effectiveness of the discussions.
C. None of the panel members know each other outside of the study.
- While familiarity can enhance communication and rapport, not knowing each other does not necessarily threaten the effectiveness of the panel, as long as they can communicate and collaborate effectively during meetings.
D. The panel members are all different ages.
- Different ages can bring diverse perspectives and insights, which can be beneficial. Age diversity itself does not inherently threaten the effectiveness of the panel.
Based on this analysis, the option that most clearly threatens the effectiveness of the panel is:
B. Jim gets mad at the rest of the panel, turns in his diary, and quits the panel.