Step 1: Understanding the Concept:
This question is about the Indian parliamentary system. The Rajya Sabha, or the Council of States, is the upper house of the Parliament of India. An "ex-officio" chairman is a person who holds the position by virtue of holding another office.
Step 2: Detailed Explanation:
According to Article 64 and Article 89(1) of the Constitution of India, the Vice-President of India is the ex-officio Chairman of the Rajya Sabha. This means that whoever holds the office of the Vice-President automatically presides over the sessions of the Rajya Sabha. The Chairman's role is to maintain order and decorum in the house. The other roles are:
(A) The President: is the Head of State.
(B) The Prime Minister: is the Head of Government.
(C) The Speaker of Lok Sabha: is the presiding officer of the Lok Sabha, the lower house.
Step 3: Final Answer:
The Vice-President of India is the ex-officio Chairman of the Rajya Sabha. Therefore, option (D) is the correct answer.