Answer:
Temperature is most likely the reason of protein unfolding (denaturation).
Explanation:
In the figure attached, coiled (3-dimensional) protein structure is changed to 2 dimensional structure in which protein is unfolded. This is most likely the result of heating proteins which destroys the hydrogen bonds and non-polar hydrophobic interactions that are necessary to establish the tertiary structure of proteins. Principally, increased temperature results in the increased kinetic energy of atoms within a molecule. If the amount of heat is sufficient to break the hydrogen bonds, protein molecule can unfold to 2D structure as shown in the figure.
