What are the two conditions under which parties may be permissibly joined?

The correct answer highlights the essential criteria for permissive joinder of parties in civil litigation. Under the Federal Rules of Civil Procedure, parties may join their claims in a lawsuit when two primary conditions are satisfied: first, the claims must arise from the same transaction or occurrence; second, there must be a common question of law or fact related to those claims.

This rule is designed to promote judicial efficiency and avoid multiple lawsuits by allowing related disputes to be resolved in a single forum. When multiple claims stem from the same incident, and similarly revolve around shared legal or factual issues, it ensures that the court can address all intertwined matters in one proceeding.

Considerations for the other options emphasize the need for commonality and relatedness among claims but do not satisfy the requirements for permissive joinder as specifically articulated in the Federal Rules. For instance, claims arising from different transactions or occurrences or that require a different set of parties would not be appropriate for joinder under the provided framework. Therefore, the focus on both the commonality in legal/factual issues and the context of transactions creates a clear pathway for joining parties effectively in litigation.