Explanation:

- A, B, and C made a joint promissory note at Benaras and delivered it to A.

- A can sue B and C at Benaras, where the cause of action arose.

- Option 1: A can sue B at Calcutta, where B resides. However, if C objects as the non-resident defendant, the court's leave is required to proceed.

- Option 2: A can sue C at Delhi, where C resides. But if B objects as the non-resident defendant, the court's leave is required.

- Option 3: Either (A) or (B). This means both locations are possible with conditions stated in options 1 and 2.

- Option 4: None of these, which doesn't apply because there are conditions under which suing is feasible.

Option 3 is the correct answer as A can indeed sue in either Calcutta or Delhi, with the necessary conditions met.