I'm thinking it might be fossil evidence. Hope it helps!
An enzyme inhibitor works as a combination in order to slow down the rate of an enzyme-catalyzed reaction. In order for an enzyme inhibitor to do this, it impacts the of "S" and/or the turn over number. An enzyme inhibitor can also be organic or inorganic and can be found in drugs or antibiotics.
I believe the correct answer from the choices listed above is the third option. It is oxygen that is a necessary reactant for cellular respiration to occur. Cellular respiration, in a sense, is breaking down sugar in the presence of oxygen. Hope this answers the question.
