What factor contributes to an animal being labeled as a top breed? the ability to reproduce
the existence of desirable traits
the specified size or weight
the presence of special markings

i think the answer is b.

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