Question

an enzyme that breaks down sucrose. activation energy sucrase enzyme substrate complex substrate

Explanation:

Enzymes are specific to their substrates. Sucrose is the substrate, and the enzyme that breaks down sucrose is sucrase. Activation energy is the energy needed for a reaction, enzyme - substrate complex is the intermediate formed when enzyme and substrate bind, and substrate is the molecule acted upon by the enzyme. So the enzyme that breaks down sucrose is sucrase.

Answer:

B. Sucrase