Manipur attained the status of a full-fledged state within the Indian Union in the year:

The correct answer is: c) 1972.

Manipur attained the status of a full-fledged state within the Indian Union on 21 January 1972. It was previously a part of the state of Assam.

Option a) is incorrect because Manipur became a Union Territory in 1956.

Option b) is incorrect because Manipur became a full-fledged state in 1972, not 1962.

Option d) is incorrect because Manipur became a full-fledged state in 1972, not 1987.