A set of reasons explaining an action is called rationale. The term you're looking for is "rationale." Rationale refers to the underlying reasons or justification for a particular action, decision, or belief.
Rationale is a noun that refers to the fundamental reasons or logical basis behind a decision, action, or belief. It provides an explanation or justification for why something was done or why a particular course of action was chosen. When someone asks for the rationale behind a decision, they are seeking an understanding of the thought process or reasoning that led to that decision.
For example, if a company decides to implement a new policy, they might present the rationale behind it, outlining the reasons and benefits that support the decision. In academic or research contexts, a rationale is often included in papers or proposals to clarify the purpose and justification for the study or project.
Complete question
A set of reasons explaining an action is called what?