Which of the following correctly represents the chemical composition of a nucleotide?

The question asks to identify the correct chemical composition of a nucleotide.

A nucleotide is the fundamental building block of nucleic acids (DNA and RNA). It is composed of three main parts:

• A pentose sugar (a 5-carbon sugar, either deoxyribose or ribose).
• A nitrogenous base (adenine, guanine, cytosine, thymine, or uracil).
• One or more phosphate groups (derived from phosphoric acid).

• A) 5-C যুক্ত শর্করা + ফসফরিক অ্যাসিড = নিউক্লিওটাইড (5-C sugar + phosphoric acid = nucleotide). This option is missing the nitrogenous base.
• B) N₂ যুক্ত ক্ষারক + ফসফরিক অ্যাসিড = নিউক্লিওটাইড (N₂ base + phosphoric acid = nucleotide). This option is missing the 5-C sugar.
• C) 5-C যুক্ত শর্করা + N₂ যুক্ত ক্ষারক = নিউক্লিওটাইড (5-C sugar + N₂ base = nucleotide). This combination forms a nucleoside, not a nucleotide, as it lacks the phosphate group.
• D) 5-C যুক্ত শর্করা + N₂ যুক্ত ক্ষারক + ফসফরিক অ্যাসিড = নিউক্লিওটাইড (5-C sugar + N₂ base + phosphoric acid = nucleotide). This option correctly includes all three components: a 5-carbon sugar, a nitrogenous base, and phosphoric acid (phosphate group).

Based on the definition of a nucleotide, option D is the correct statement.

The final answer is $\boxed{\text{D}}$