Topic: Article,

Best Answer Explained in Below-:

The correct answer to the phrase "I'll be with you in-" is B) "a quarter of an hour." This option is optimal due to its grammatical accuracy and common usage in English.

Firstly, “a quarter of an hour” is an idiomatic expression that denotes a period of 15 minutes, and it is widely understood and accepted in both spoken and written English. The inclusion of the article "a" makes the phrase complete and sounds natural in conversation.

Option A, "one quarter of an hour," is grammatically correct but less common in everyday use. While it conveys the same meaning, the phrase sounds more formal and is not as succinct as option B.

Option C, "a quarter of one hour," is also grammatically correct but is unnecessarily verbose and clumsy. This redundancy makes it less appealing.

Finally, option D, "quarter of hour," is incorrect due to the omission of the article “an” or “a,” which is essential in English to specify singular nouns.

In summary, option B is not only grammatically correct but also the most conventional and natural way to express the time interval in everyday speech.