The correct answer is D. An
Explanation:
In grammar, an article is a word that precedes nouns and that shows whether the noun is general or specific. In the case of the English language, the articles are the and a/an. Also, these articles are classified as definite articles in the case of the article "the" as this defines a particular entity or as indefinite articles, in the case of a/an because these refer to a general entity. Therefore, in the case of the sentence "Her mother always said that it is important to do an honest day’s work" the indefinite article is "an" as this precedes the noun "an honest day's work" and refers to a specific idea or entity.
