Correct option is C
The correct option to fill in the blank is (c) Permission.
Explanation: The word "permission" is the most appropriate, as students require approval to leave.
Meanings of other options:
· Tolerance: The ability to endure something, not suitable for this context.
· Indulgence: Excessive leniency or allowance, inappropriate here.
· Freedom: The power or right to act, but doesn't fit the meaning of seeking approval.