The correct option is
A Den
Nouns are naming words. For example: 'Ram is a boy.' Here, both 'Ram' and 'boy' are nouns. 'Ram' is a proper noun and 'boy' is a common noun. There are different types of nouns; i.e.; proper nouns, common nouns, material nouns, abstract nouns, concrete nouns, countable nouns, uncountable nouns, compound nouns and collective nouns.
NOTE: The given options are all common nouns.
Option B - A chicken lives in a coop. Hence, option B is incorrect.
Option C - A mouse or a chipmunk lives in a tunnel. Hence, option C is incorrect.
Option D - A termite lives in a mound. Hence, option D is incorrect.
Option A - A fox lives in a den. Hence, option A is the correct answer.
'A den of a fox.'