For an exothermic reaction $A \to B$,the activation energy is $65 \ kJ \ mol^{-1}$ and the heat of reaction is $-42 \ kJ \ mol^{-1}$. The activation energy for the reverse reaction $B \to A$ would be....... $kJ \ mol^{-1}$

• A
  $23$
• B
  $107$
• C
  $65$
• D
  $42$