Step 1: Understanding the Concept:
The term 'public servant' is defined exhaustively in Section 21 of the Indian Penal Code, 1860. The question requires identifying which of the given options does not fall within the ambit of this definition.
Step 2: Detailed Explanation:
Let's examine each option against the clauses of Section 21, IPC:
- (A) A Liquidator: The Fourth clause of Section 21 includes "Every... officer of a Court of Justice... whose duty it is, as such officer, to... take, keep or expend any property...". A liquidator appointed by a court or a tribunal (like the NCLT) is considered an officer of the court and hence, a public servant.
- (B) A Civil Judge: The Fourth clause of Section 21 explicitly includes "Every Judge...". Therefore, a Civil Judge is a public servant.
- (C) Secretary of a Co-operative Society: This is the crucial point. A co-operative society is a body registered under the respective State Co-operative Societies Act. It is an autonomous association of persons. The Supreme Court of India in several cases, notably in \textit{State of Maharashtra v. Laljit Rajshi Shah} and \textit{S.S. Dhanoa v. Municipal Corporation, Delhi}, has held that an employee of a co-operative society is not a public servant within the meaning of Section 21 of the IPC. This is because a co-operative society is not a 'corporation established by or under a Central, Provincial or State Act' (which would fall under the Twelfth clause), but is merely a body registered under such an Act.
Therefore, the Secretary of a Co-operative Society is not a public servant under the IPC. (Note: They may be deemed public servants for the purposes of specific acts, like the Prevention of Corruption Act, under certain circumstances, but not under the general definition in the IPC).