The lock-and-key mechanism refers to a) the complementary shapes of an enzyme and a substrate. b) the attractive forces between an enzyme and a substrate. c) the ability of an enzyme to lower the activation energy of a reaction. d) the ability of an enzyme to “unlock” the products of a reaction.

A. The complementary shapes of an enzyme and a substrate

Explanation:

The Lock-and-Key model was made to show how an enzyme's active zone fits a substrate and how they bond together. It correlates just like a lock and a key; you have to have the correct-shaped key in order to open a lock. Same process of thought with the enzymes; you must have the same shape for both in order to bind together,

not sure if this what   you'r looking for would be percent composition