Two monomers in maltose are

• A
  $\alpha-D$-glucose and $\beta-D$-glucose
• B
  $\alpha-D$-glucose and $\alpha-D$-fructose
• C
  $\alpha-D$-glucose and $\alpha-D$-glucose
• D
  $\alpha-D$-glucose and $\alpha-D$-galactose