Snails, when repeatedly touched with no harm intended, stop pulling their heads back into their shells. what type of behavior does this example represent?

Habituation

Explanation:

Over time of the snail experiencing said repeated action it eventually grows used to it and knows it doesn't need to hide.

enzyme active site and substrate specificity

enzymes bind with chemical reactants called substrates. there may be one or more substrates for each type of enzyme, depending on the particular chemical reaction. in some reactions, a single-reactant substrate is broken down into multiple products