$Assertion (A)$: van der Waals' forces are responsible for chemisorption. $Reason (R)$: High temperature is favourable for chemisorption. The correct answer is

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