Topic: Article,

Best Answer Explained in Below-:

The phrase "This is __ unique opportunity" requires an appropriate article to fill in the blank, and the correct choice is "a." This can be understood by examining the rules of English usage regarding articles.

The word "unique" begins with a consonant sound (/juː/), which normally would lead one to use "a" instead of "an." The article "a" is utilized before singular nouns that begin with a consonant sound, while "an" is reserved for singular nouns that begin with a vowel sound. Consequently, "a unique opportunity" fits this rule perfectly.

Moreover, the use of the article "a" in this context implies that this specific opportunity is one among potentially many others. If we had chosen "the," the phrase would suggest that the opportunity is one of a kind or has already been specified, which changes the intended meaning. Since the sentence introduces a general notion of a unique opportunity rather than a specific or previously mentioned one, "a" serves to denote its singular but not exclusive nature.

In summary, using "a" accurately reflects the intended meaning and adheres to English grammatical conventions concerning articles.