Correct Answer: Dormitory

Solution : The correct choice is the first option.

Explanation :

A dormitory is a large bedroom for a number of people in a school or institution. It is a collective sleeping arrangement typically found in colleges or public institutions. The term specifically denotes sleeping rooms in such settings.

Therefore, the correct one-word substitute is dormitory.

The meanings of the other options are as follows:

• Convent : This term refers to a community of people, especially nuns, living together under religious vows.
• Monastery : This term refers to a building or buildings occupied by a community of monks living under religious vows.
• Arsenal : This term refers to a place where weapons and military equipment are stored or made.