Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A) : Aluminium is extracted from bauxite by the electrolysis of molten mixture of ${\mathrm{Al}}_2{\mathrm{O}}_3$ with cryolite.
Reason (R) : The oxidation state of $\mathrm{Al}$ in cryolite is $+3.$
In the light of the above statements, choose the most appropriate answer from the options given below :

• A

  Both (A) and (R) are correct and (R) is the correct explanation of (A).
• B

  (A) is true but (R) is false.
• Correct answer
  C

  Both (A) and (R) are correct but (R) is not the correct explanation of (A).
• D

  (A) is false but (R) is true.

Hence, the correct answer is option: 'C'.