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.

"Maltose" disaccharide is composed of

Two $α$-D-glucose units

The correct answer is Option (1) → Two $α$-D-glucose units **

Maltose is a disaccharide formed by the condensation of two molecules of α-D-glucose.

These two glucose units are linked by an α(1→4) glycosidic bond.

Structure: α-D-glucose — α(1→4) — α-D-glucose

Because one anomeric carbon remains free, maltose behaves as a reducing sugar.

Option 1 Two α-D-glucose units-- Correct. Maltose consists of two α-D-glucose molecules linked through an α(1→4) glycosidic bond.

Option 2 α-D-glucose and β-D-fructose

Incorrect. This combination forms sucrose, not maltose.

Option 3 β-D-galactose and β-D-glucose

Incorrect. This forms lactose, not maltose.

Option 4 α-D-glucose and β-D-glucose

Incorrect. Maltose contains two glucose units in α form, not α and β together