Topic: Article,

Best Answer Explained in Below-:

In the sentence "It is quarter __ to six," the correct choice is "a." This usage stems from the way we describe time in English, specifically when indicating fractions of an hour using "quarter."

The term "quarter" refers to a quarter of an hour, which equals 15 minutes. When speaking about time, we often use the indefinite article "a" to refer to a single unit or instance of something that is not specifically defined. In this case, "a quarter" means one quarter of an hour, which is a common and idiomatic way to express time.

Using "the," which denotes something specific, would not be appropriate here because "quarter" in this context refers to any quarter hour rather than a particular one. "An" is incorrect as "quarter" does not start with a vowel sound, and "that" does not fit grammatically at all.

Thus, the correct form is "It is quarter **a** to six," accurately indicating a generic reference to a single quarter of an hour before reaching six o'clock.