Explanation:

- The Prime Minister is obligated to advise the President on matters where advice is sought, aligning with parliamentary privileges and responsibilities.

- Option 1: If the Council of Ministers so desires.

- It suggests the Prime Minister’s advice is contingent upon the Council's desire, which is incorrect. The role mandates him to advise the President routinely.

- Option 2: Yes.

- The Prime Minister, by constitutional convention, is always required to offer advice to the President when requested.

- Option 3: No.

- This is incorrect. The Prime Minister cannot refuse to offer necessary advice to the President.

- Option 4: It is discretionary.

- This is incorrect as well. The advisory role is not discretionary for the Prime Minister.