Given below are two statements: one is labelled as Assertion $A$ and other is labelled as Reason $R.$
Assertion $A :$ Sucrose is a disaccharide and a non-reducing sugar.
Reason $R :$ Sucrose involves glycosidic linkage between $C_{1}$ of $\beta$-glucose and $C_{2}$ of $\alpha$-fructose.
Choose the most appropriate answer from the options given below :

• A
  Both $A$ and $R$ are true but $R$ is not the true explanation of $A$.
• B
  $A$ is false but $R$ is true.
• C
  $A$ is true but $R$ is false.
• D
  Both $A$ and $R$ are true and $R$ is the true explanation of $A$.