Select the correct statement about what a catalyst actually does in a chemical reaction.

Introduction / Context:
The essence of catalysis is kinetic acceleration without altering equilibrium. This question tests the core principle behind catalytic rate enhancement.

Given Data / Assumptions:

• Standard catalytic cycle: catalyst participates transiently but is regenerated.
• No catalyst poisoning or side reactions considered.

Concept / Approach:
Rate constants depend on activation energy or activation free energy. A catalyst provides an alternative pathway with a smaller barrier, increasing k at the same temperature via k ∝ exp(-ΔG‡/(R*T)).

Step-by-Step Solution:
1) Identify how to increase rate at fixed temperature: lower the activation barrier.2) A catalyst interacts to form intermediates/transition states, then is regenerated; it is not consumed overall.3) Since ΔG° is unchanged, the equilibrium constant is unchanged; only the time to reach equilibrium is reduced.

Verification / Alternative check:
Experimental observation: changing catalyst affects rate but not final equilibrium composition—consistent only with a barrier-lowering mechanism.

Why Other Options Are Wrong:
Option a/d: Catalysts are regenerated; they are not consumed.
Option b: A catalyst does more than “initiate”; it changes ΔG‡.
Option e: Equilibrium (ΔG°) is unchanged by a catalyst.

Common Pitfalls:
Equating faster rate with different equilibrium; assuming catalyst is a reagent.

Final Answer:
A catalyst lowers the activation energy / activation free energy.