Biomolecules

Statement I:
"Lactose is composed of α-D-glucose and β-D-glucose."
Recall:
Lactose (milk sugar) is a disaccharide consisting of β-D-galactose and β-D-glucose, linked by a β(1⟶4) glycosidic bond:
β-D-Galactose - (1⟶4) - β-D-Glucose.
Therefore, it is not composed of two glucose molecules - one of the units is galactose.
Hence, Statement I is incorrect.
Statement II:
"Lactose is a reducing sugar."
Explanation:
In lactose, the glucose unit still has a free anomeric carbon (the hemiacetal group), so it can undergo mutarotation and reduce Benedict's or Fehling's solution.
Thus, lactose is a reducing sugar.
Statement II is correct.