Institution: জাতীয় কবি কাজী নজরুল ইসলাম বিশ্ববিদ্যালয় (JKKNIU) Exam: ক ইউনিট || জাতীয় কবি কাজী নজরুল ইসলাম বিশ্ববিদ্যালয় || 2013
Topic: Correction (Sentence Correction), Subject: English Grammar (ইংরেজি গ্রামার)

Best Answer Explained in Below-:

The correct choice, D) "He is a hardworking young man," is a simple and grammatically correct sentence that combines the two attributes—youth and diligence—into a coherent phrase. This sentence effectively communicates that the subject, "He," possesses both qualities without unnecessary complexity.

Each of the other options presents structural or grammatical issues that make them incorrect.

A) "He is a young man hardworking," incorrectly places the adjective "hardworking" at the end of the sentence. This disrupts the natural flow and doesn't align with standard English sentence structure.

B) "He is a young man a quality of hard work." is awkward and unclear; it awkwardly tries to define "hard work" without proper grammatical support, resulting in a fragment rather than a complete thought.

C) "He is a young man doing work hard." also fails grammatically by misusing "doing work" which adds unnecessary complexity, and "hard" should be "hardworking" to convey the intended meaning.

Option D succinctly synthesizes the two qualities into one structured adjective, making it the best representation of the original idea.