An agent, at the time of making the contract, does not disclose the name and address of his principal but it becomes known to the second party afterwards. In case of any default, the second party may file a suit against:

Correct option is C

Under Section 230 of the Indian Contract Act, when the agent does not disclose the principal’s identity at the time of contracting, both the agent and the principal can be held liable.
Information Booster:
The second party has the right to sue either the agent, the principal, or both, depending on the circumstances, once the principal’s identity is known.
Additional Information:
· Options (a) and (b): Liability isn't restricted to one party; both can be held liable.