Explanation:

Here’s the thing.

Let’s break it down, bullet by bullet:

- Chief Justice of India: Parliament can’t usually invite the Chief Justice to give an opinion. He is the head of the Judiciary and stays out of the Legislature’s proceedings to keep a clear separation of powers.

- Chief Election Commissioner of India: Same story. He heads the Election Commission, which stays independent and doesn’t advise Parliament as a matter of process.

- Comptroller & Auditor-General of India (CAG): The CAG submits audit reports to Parliament, but is not “invited” for opinions or advice in the same way.

- Attorney-General of India : Now, here’s the key. The Attorney-General is the only one who’s specifically meant to advise Parliament. In fact, the AG has the right to be present in parliamentary proceedings and can express his views when needed.

So, the right answer is Option 4: Attorney-General of India. Only he fits the bill for this question.