The correct answer is option 4 - 1975. National emergency in India can be declared by the President of India on the grounds of internal disorder under Article 352 of the Indian Constitution. In 1975, then-Prime Minister Indira Gandhi recommended the imposition of a national emergency to President Fakhruddin Ali Ahmed, and it was approved. This period, often referred to as the "Emergency," lasted from 1975 to 1977. During this time, civil liberties were suspended, freedom of the press was curtailed, and many political opponents were arrested. The Emergency was lifted in 1977, following widespread protests and the defeat of the ruling party in the general elections.