The right answer is C. begins to denature above 25°C
In biochemistry, denaturation is the process by which a biological macromolecule, nucleic acid or protein loses its normal three-dimensional conformation: the proteins lose their folding and unfold, the paired strands of the nucleic acid duplexes separate. This three-dimensional conformation is most often necessary so that the biological macromolecules can fulfill their function and thus the inactive denaturation in general these biological macromolecules.
Denaturation can be done by:
*Temperature: The increase in temperature causes thermal agitation of the atoms of the molecule. This causes a break in intermolecular interactions.
*Chemical agents: chaotropic agents, bases, acids, reducing agents, detergents, heavy metal ions.
The reaction is slow because the molecules are moving slowly and they will not often collide with the active site of an enzyme, so the binding of an enzyme and substrate is rare.