The correct answer is option 1, Internal Emergency. An Internal Emergency, also known as a National Emergency, is declared when there is a threat to the sovereignty and integrity of India. It can be declared due to war, external aggression, or armed rebellion. This type of emergency has been imposed only once in India`s history. It was declared in 1975, by then-Prime Minister Indira Gandhi, due to political unrest and a deteriorating law and order situation. During this period, civil liberties were suspended, and the central government gained significant control over the states. It lasted for a period of 21 months and was lifted in 1977 after the general elections. It is important to note that an Internal Emergency is a grave situation and should be implemented only under extreme circumstances.