Read the passage carefully and answer the questions:

Optically active polyhydroxy aldehydes or ketones or molecules which provide such units on hydrolysis are called carbohydrates. They can be broadly classified as monosaccharides, disaccharides and polysaccharides depending on their behavior towards hydrolysis. They are also classified as reducing or non reducing sugars. Another class of biomolecules is proteins which are polymers of twenty different amino acids linked by peptide bonds. Amino acids can be classified as acidic, basic or neutral depending on the relative number of amino and carboxyl groups in their molecule. The essential amino acids cannot be synthesized by our body and hence must be provided through diet. Nucleic acids are the polymers of nucleotides which in turn consist of a base, pentose sugar and phosphate. There are two types of nucleic acids namely, DNA and RNA which differ in the composition of sugar and a base.

The sugar moiety in DNA and RNA molecules, respectively, are

$β$-D-2-deoxyribose and $β$-D-ribose

The correct answer is Option (2) →$β$-D-2-deoxyribose and $β$-D-ribose

Nucleic acids consist of three components: • Nitrogenous base • Pentose sugar • Phosphate group

The type of pentose sugar distinguishes DNA from RNA.

DNA (Deoxyribonucleic Acid) The sugar present in DNA is β-D-2-deoxyribose.

It differs from ribose because the 2nd carbon lacks an oxygen atom, having H instead of OH. Thus it is called deoxyribose.

RNA (Ribonucleic Acid) The sugar present in RNA is β-D-ribose. Here the 2nd carbon contains an –OH group, making it ribose.

Hence, Option 2 --  β-D-2-deoxyribose and β-D-ribose

Correct.

DNA contains $β$-D-2-deoxyribose and RNA contains $β$-D-ribose