The rate of a reaction can be expressed by the Arrhenius equation as:
$k = A e^{-E_a / RT}$
In this equation,$E_a$ represents:

• A
  the total energy of the reacting molecules at a temperature,$T$
• B
  the fraction of molecules with energy greater than the activation energy of the reaction
• C
  the energy above which all the colliding molecules will react
• D
  the energy below which all the colliding molecules will react