Final answer:
Coalition formation is impossible in a dyad, as it ceases to exist if one member withdraws, unlike in a triad or larger groups where coalitions can form among the remaining members.
Step-by-step explanation:
Coalition formation is impossible in a dyad, which is a two-member group. This is because when one person withdraws from a dyad, the group ceases to exist entirely. For example, consider a divorce, which ends the dyad group of a married couple, or the case of two best friends who cease communication. The dynamic in a triad, however, is different. If one person withdraws, the group still survives because at least two members remain, allowing for the potential formation of coalitions within the group.