In the lock-and-key model of enzyme action, the fits into the of the enzyme. a. product; substrate. b. active site; product. c. substrate; active site. d. active site; substrate.

The answer is letter D. Substrate; Active Site The enzyme itself remains unchanged.  It advise the active place of an enzyme is frequently reshaped by interactions with the substrate until the substrate is completely bound and the chemical reaction occurs, the lock and key model.

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the answer would be knowledge about cars!