Span of management refers to:

1. Number of subordinates at lower level
2. Total number of managers
3. Number of subordinates under a superior
4. Number of levels in the organisation

Option 1 -> This is incorrect as span of management is not limited to only lower-level subordinates but applies to any manager at any level.

Option 2 -> This is incorrect as span of management does not refer to counting the total managers in an organization.

Option 3 -> This correctly defines span of management as the number of subordinates directly reporting to a manager or superior.

Option 4 -> This is incorrect as the number of organizational levels refers to the organizational hierarchy or chain of command, not span of management.

Hence, Option 3: Number of subordinates under a superior -> Span of management (also called span of control) is a fundamental management principle that refers to the number of subordinates who report directly to a manager or supervisor. It determines how many employees one manager can effectively supervise and manage. -> correct