Which statement correctly describes the effect of a catalyst on the potential-energy diagram of a multistep reaction?
a) It decreases the activation energy for the forward reaction but increases that for the reverse reaction, thereby shifting the equilibrium toward products while leaving ΔH unchanged.
b) It lowers the activation energy of every elementary step while leaving the overall ΔH of the reaction unchanged.
c) It eliminates the high-energy intermediates so the multistep mechanism becomes a single elementary step with the same ΔH.},{
d) It lowers the activation energy only for the rate-determining step, which makes the overall ΔH more negative.