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

The joint session of the Indian Parliament is presided over by the Speaker of Lok Sabha. Let's understand this in detail:

1. Definition of Joint Session:
A joint session of the Parliament is a special session where both houses of the Parliament, i.e., the Lok Sabha (House of the People) and the Rajya Sabha (Council of States), come together to conduct legislative business. This session is called by the President of India in certain situations.

2. Role of the Speaker of Lok Sabha:
The Speaker of Lok Sabha is the presiding officer of the lower house of the Parliament. The Lok Sabha is the directly elected house of the Parliament and represents the people of India. The Speaker is responsible for maintaining decorum, ensuring smooth functioning, and conducting the proceedings of the Lok Sabha.

3. Power to Preside over Joint Session:
According to Article 118 of the Indian Constitution, the Speaker of Lok Sabha has the power to preside over a joint sitting of both houses of Parliament. When a joint session is called by the President, the Speaker assumes the role of the presiding officer for that session. This means that the Speaker has the authority to preside over and regulate the proceedings of the joint session.

4. Reason behind Speaker's Role:
The reason behind the Speaker of Lok Sabha presiding over the joint session is to maintain the principle of equality between the two houses. Since the Lok Sabha is directly elected by the people, it is considered to be the representative of the people's will. By having the Speaker preside over the joint session, the voice of the people, as represented by the Lok Sabha, is given prominence.

5. Importance of Joint Session:
A joint session of Parliament is called when there is a deadlock between the two houses on a particular bill or when the Rajya Sabha fails to pass a bill that has been passed by the Lok Sabha. In such cases, the joint session is convened to resolve the deadlock and ensure that legislation is not hindered.

In conclusion, the Speaker of Lok Sabha presides over the joint session of the Indian Parliament. This role is crucial in maintaining the balance between the two houses and ensuring the smooth functioning of legislative business.