Step 1: Term Definitions.
- Rule: A directive or regulation mandating specific actions or behaviors; it dictates what must be done or omitted.
- Policy: A set of guiding principles or frameworks that inform decision-making but may not be as precise about actions as a rule.
- Strategy: A plan or method designed for achieving objectives, generally broader than a rule.
- Procedure: A sequence of actions for task completion, which may not specify whether an action should or should not be taken.
Step 2: Option Analysis.
- Rule aligns with the definition of a specific, definitive action or inaction. - Policy, Strategy, and Procedure differ in their definition of specific actions compared to a rule.
Final Answer: \[\boxed{\text{The correct answer is (1) Rule.}}\]