Catalysts lower activation energy without altering molecular energy distribution Steps:

• Catalysts provide a pathway with reduced activation energy E_a, increasing reaction rate.
• Maxwell-Boltzmann distribution shows energy distribution of molecules, fixed by temperature.
• Peak of distribution (most probable energy) stays same height and position with catalyst.
• E_a line shifts left to lower energy on x-axis (energy increasing rightward), increasing molecules above E_a.

Why B is correct:

• Collision theory states catalysts decrease E_a (moving its position left), leaving distribution curve unchanged per Boltzmann distribution f(E) = (2/√π)(E^{1/2}/(kT)^{3/2}) exp(-E/kT).

Why the others are wrong:

• A: Peak height unchanged; catalyst does not modify energy distribution.
• C: E_a moves left (lower), not right (higher E_a would slow reaction).
• D: Peak height and E_a position both unaffected or wrongly shifted.

Final answer: B