The answer to this is A.
Enzymes are proteins that acts as a biological catalysts that can speed up chemical reactions, by binding substrates to its active site and releasing products. They're not changed by the reaction.
Enzymes are specialized, which means they only binds to a certain substrate, so it's not B.
Activation energy is the energy required for chemical reactions, enzymes can actually lower the energy for the chemical reaction so its not C.
Again, enzymes are biological catalysts that speeds up reactions, so it's not D.
Yes, enzyme activity depends on the temperature and the pH. Each enzyme has a different optimum pH and temperature that best works for them. They may be slower if the pH or temperature does not fit them. If the pH get too extreme, or the temperature gets to high, the enzyme will be denatured and can no longer bind into substrates. Their active sites are changed.
