The word that best describes disputes within a discussion is unnecessary.
Explanation:
- Unnecessary implies that the disputes do not contribute positively to the discussion and could be avoided for a more productive dialogue.
- The other options, while they may have their contexts, do not capture the idea of disputes in a discussion as well as "unnecessary" does.
- Useful implies that the disputes add value, which is often not the case.
- Comfortable does not relate to the nature of disputes.
- Avoidable suggests that disputes could be sidestepped but doesn't directly imply they are detrimental or out of place in the discussion.
Thus, "unnecessary" effectively characterizes disputes that can detract from the overall purpose of a discussion.