Explanation:

- If a person, after being summoned under Section 91 of CrPC, fails to attend or produce the required document/thing:

- Option 1: A search warrant can be issued under Section 93 of CrPC to recover the document/thing.

- Option 2: A prosecution can be launched against the person under Section 175 of the Indian Penal Code (IPC) for non-compliance.

- Option 3: "Either (a) or (b)" means the authority has the discretion to choose one of the two options based on circumstances.

- Option 4: "Both (a) and (b)" suggests that both actions can be taken simultaneously.

- Legally, either action can be taken, but not necessarily both at the same time; it is generally a case-based decision to opt for one.

- Option 3—either (a) or (b)—is correct.