The correct answer is (a) Chief Justice of India.
The President shall obtain the opinion of the Chief Justice of India before deciding any question relating to the disqualification of a member of Parliament. This is provided for in Article 102(2) of the Constitution of India.
The Election Commission of India is responsible for conducting elections to Parliament and state legislatures. It is not responsible for deciding questions relating to the disqualification of members of Parliament.
The Attorney General of India is the principal legal adviser to the Government of India. He is not responsible for deciding questions relating to the disqualification of members of Parliament.
The Speaker of the Lok Sabha is the presiding officer of the Lok Sabha, the lower house of Parliament. He is not responsible for deciding questions relating to the disqualification of members of Parliament.
The President is the head of state of India. He is responsible for deciding questions relating to the disqualification of members of Parliament. However, he is required to obtain the opinion of the Chief Justice of India before doing so.