The correct answer is option 'D': Speaker of Lok Sabha.

The Joint Session of the Indian Parliament is a session where both houses of Parliament, the Lok Sabha (House of the People) and the Rajya Sabha (Council of States), assemble together. This session is convened in certain specific situations as mentioned in Article 108 of the Constitution of India.

Here's a detailed explanation of why the Speaker of Lok Sabha presides over the Joint Session of the Indian Parliament:

1. Role of Speaker:
The Speaker of Lok Sabha is the presiding officer of the Lok Sabha, which is the lower house of Parliament. The Speaker is responsible for maintaining order and discipline in the house, conducting its proceedings, and interpreting the rules of procedure.

2. Joint Session:
A Joint Session of Parliament is called in two situations:
a) When a bill passed by one house is rejected by the other, or amendments made by one house are not accepted by the other.
b) When the President of India wants to address both houses of Parliament.

3. Presiding Officer:
During a Joint Session, the Speaker of Lok Sabha presides over the proceedings. This is because the Speaker is considered the senior-most member of Parliament and holds a position of authority and impartiality.

4. Special Powers of Speaker:
The Speaker has certain special powers while presiding over the Joint Session. These include the power to regulate the procedure of the session, decide on points of order and questions of privilege, and maintain decorum and discipline.

5. Role of Rajya Sabha Chairman:
The Chairman of Rajya Sabha, who is the presiding officer of the upper house, does not preside over the Joint Session. In the Joint Session, the Chairman of Rajya Sabha sits in the same position as other members of Parliament.

In conclusion, the Speaker of Lok Sabha presides over the Joint Session of the Indian Parliament due to their role as the presiding officer of the lower house and their authority and impartiality in conducting parliamentary proceedings.