When the reader is aware of the precise identity of the noun, as in the following cases, use the definite article before any noun (singular, plural, countable, or noncount). When a specific noun has already been specified, use the article "the. When an adjective, phrase, or clause characterising the noun explains or limits its identity, use the article "the. When a noun refers to something or someone special, use the article the. 'The' is a superlative prefix. When a noun refers to an entire class, "the" is used; hence option B is not a use of a definite article.