The sugar molecule present in nucleotide is

The correct option is pentose.

To understand why this is the correct answer, let us break down the structure of a nucleotide step-by-step:

1. What is a Nucleotide?
A nucleotide is the basic building block of nucleic acids, such as DNA (deoxyribonucleic acid) and RNA (ribonucleic acid). Every nucleotide is composed of three distinct chemical components:
- A nitrogenous base (adenine, guanine, cytosine, thymine, or uracil)
- A phosphate group
- A pentose sugar (ribose or deoxyribose)

2. Analyzing the Sugars based on Carbon Count:
Sugars (carbohydrates) are classified based on the number of carbon atoms present in their molecular skeleton:
- Triose sugars contain 3 carbon atoms (e.g., glyceraldehyde).
- Tetrose sugars contain 4 carbon atoms (e.g., erythrose).
- Pentose sugars contain 5 carbon atoms (e.g., ribose, deoxyribose).
- Hexose sugars contain 6 carbon atoms (e.g., glucose, fructose).

3. The Sugar in Nucleotides:
The sugar molecule present in DNA is 2-deoxyribose, and the sugar present in RNA is ribose. Both ribose ($C_5{H}_{10}{O}_5$) and deoxyribose ($C_5{H}_{10}{O}_4$) contain exactly five carbon atoms in their ring structure. Therefore, the sugar molecule in a nucleotide is classified as a pentose sugar.