Correct Option: B

National emergency is caused by war, external aggression or armed rebellion in the whole of India or a part of its territory. Such an emergency was declared in India in 1962 (Indo-China war), 1971 (Indo-Pakistan war), and 1975 (declared by Indira Gandhi to escape conviction). The President can declare such an emergency under Article 352 of the Constitution only on the basis of a written request by the Council of Ministers headed by the Prime Minister. Such a proclamation must be approved by the Parliament within one month. Such an emergency can be imposed for six months. It can be extended by six months by repeated parliamentary approval.