Answer: D. Freezing.
Step-by-step explanation:
Proteins can be denatured by various factors, including changes in temperature, pH, chemicals, and radiation. Freezing, however, is not generally considered a denaturing factor, as it only slows down or halts the activity of proteins, rather than changing their shape or breaking their bonds. In fact, freezing is often used as a preservation technique for proteins and other biomolecules, as it can help to maintain their stability and prevent degradation over time.