Which of the following statements is correct?

a. The best enzyme can catalyze a number of different chemical reactions using a variety of substrates.
b. The substrate must be larger than the enzyme in order for a reaction to occur.
c. A substrate binds several places on a given enzyme.
d. An enzyme will generally bind only one substrate.

d. An enzyme will generally bind only one substrate.

Explanation:

Enzymes are the catalytic biomolecules. The enzymes have specific pockets called active sites. Substrates bind to these pockets of enzymes. The active site of an enzyme is compatible to allow a specific substrate to bind to it. This allows specificity to the enzymes and ensures that a specific enzyme binds to a particular substrate only. A substrate can bind to the active site of its enzyme, it can not bind to any other site of the enzyme. Moreover, substrate binding induces a conformation change in the active site of its enzyme to favor the binding of more substrate molecules.

materials water oxygen those are the things i can think of in this moment.

answer: substrate concentration. enzymes work best when there is a high enough substrate concentration for the reaction they catalyse.