Explanation:

- Option 1: Yes, if the Council of Ministers so desires

- This option suggests the Prime Minister is bound to advise when the Council of Ministers requests it. However, the Prime Minister’s role is independent of such conditional requirements.

- Option 2: Yes

- This option indicates that the Prime Minister is generally obligated to give advice in certain constitutional contexts, especially to the head of state, like the President. This obligation is part of their duties in the parliamentary system.

- Option 3: No

- This implies the Prime Minister is not obligated to advise. This is incorrect in contexts where the Prime Minister is constitutionally required to give advice.

- Option 4: It is discretionary

- This would suggest the Prime Minister can choose when to advise, which is not aligned with constitutional duties in a parliamentary system.