Answer: A. A catalyst provides an alternative reaction pathway with a lower activation energy. Both forward and backward activation energies are reduced by the same amount.
The enthalpy change \(\Delta H\) is unchanged. The catalyst is not consumed and does not appear in the overall equation, so the net energy difference between reactants and products is identical to the uncatalysed reaction. The catalyst speeds up the rate without altering the position of equilibrium or the overall energy released or absorbed.
Row A captures both points: lower \(E_a\), same \(\Delta H\). The other rows either raise \(E_a\) (impossible — that would slow the reaction) or claim \(\Delta H\) decreases (also wrong).
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