The correct answer is rule.
A rule is a specific instruction that must be followed. It is a rigid plan that leaves no room for discretion. Rules are often used to ensure safety, fairness, or efficiency. For example, a rule might require employees to wear safety goggles when using power tools. Or, a rule might require students to turn in their homework on time.
Schedules, procedures, and budgets are also plans, but they are not as rigid as rules. Schedules are plans that outline when certain tasks should be completed. Procedures are plans that outline how certain tasks should be completed. Budgets are plans that outline how money should be spent. All of these plans can be helpful, but they do not have the same level of authority as rules.
In conclusion, the correct answer is rule. A rule is a specific instruction that must be followed. It is a rigid plan that leaves no room for discretion. Rules are often used to ensure safety, fairness, or efficiency.