Step 1: List the recognised types of plans in management.
Management textbooks classify plans into: Objectives, Strategy, Policy, Procedure, Method, Rule, Programme, and Budget.
Step 2: Check Strategy.
A strategy is a comprehensive, long-term plan designed to achieve specific organisational objectives. It IS a type of plan.
Step 3: Check Procedure.
A procedure specifies the exact, step-by-step sequence of actions to perform a particular activity. It IS a type of plan (a standing plan).
Step 4: Check Policy.
A policy is a general guideline that channels decision-making within set boundaries. It IS a type of plan (a standing plan).
Step 5: Examine Mission carefully.
A mission is the broad philosophical statement that describes why an organisation exists and what it aims to do for society. It serves as the foundation upon which objectives and plans are built. However, mission itself is not classified as an operational type of plan in standard management taxonomy.
Step 6: Conclude.
Because Mission is a foundational statement rather than a specific type of plan, it is the odd one out here.
\[ \boxed{ \text{(B) Mission} } \]