Fill in the blank using the most appropriate option to form a compound noun:
The __________ chimneys are the major source of air pollution.
Compound nouns are a combination of two nouns in which the first noun is what kind of a person or object it is or what the purpose of the noun is whereas the second noun identifies the first noun.
From the given options, company is a term used for any organised commercial business; mill is used to describe a building that is equipped to make or produce something; shop is a building that is used to sell some product. A factory is a building that is used to manufacture or assemble something. To form a compound noun with chimneys, the most commonly used word is 'factory'. We never see a shop or a company have 'chimneys'. A mill may or may not be used with the word chimneys. Therefore, the most apt word that forms a compound noun with 'chimneys' is option A) factory.