Step 1: Recall constitutional provisions.
Under Articles 352, 356, and 360 of the Constitution, the power to proclaim emergency lies with the President of India.
Step 2: Process.
The President declares emergency on the advice of the Union Cabinet headed by the Prime Minister. However, the formal authority rests with the President.
Step 3: Eliminate options.
(B) Prime Minister: Only recommends, does not declare.
(C) Chief Justice: Judiciary plays no role in declaring emergency.
(D) None: Incorrect, since President does declare.
Step 4: Conclusion.
Correct answer: (A) President.