Question

when the enzyme and substrate are locked together during a chemical reaction
enzyme substrate complex
acid
activation energy
substrate

Explanation:

The question is about the term for when enzyme and substrate are locked together in a reaction. The "Enzyme Substrate Complex" is the correct term as it refers to the temporary complex formed between an enzyme and its substrate during a reaction. "Acid" is a type of chemical, "Activation Energy" is the energy needed to start a reaction, and "Substrate" is the reactant in an enzyme - catalyzed reaction, not the complex of enzyme and substrate.

Answer:

A. Enzyme Substrate Complex