The sleeping rooms in a college or public institution :

Cloakroom: a room in a public building where outdoor clothes or luggage may be left.

Gymnasium: a room or building equipped for gymnastics, games, and other physical exercise.

Dormitory: a large bedroom for a number of people in a school or institution.

Lair: a place where a wild animal, especially a fierce or dangerous one, lives.

Hence, the correct answer is option C.