Many So-Called Temperature-Sensitive Mutations Have Been Discovered in a Wide

Many so-called temperature-sensitive mutations have been discovered in a wide variety of organisms. These are proteins that are non-functional at higher temperatures, while, at lower temperatures (often just a few degrees lower) , they function normally. For example, the coloration patterns in Siamese Cats arise from a temperature-sensitive mutation. An enzyme required for the synthesis of dark pigment is unable to function in areas close to the body where normal physiological temperatures prevail. However, at the tips of the ears, paws, the tip of the tail and other extremities where the temperature is slightly lower, the enzyme works correctly and dark pigment is produced. What is happening at the molecular level that explains this?

A) the enzyme responsible for pigment production is more sensitive to cold than others in the animal cells and unfolds in the cooler environment of the extremities
B) the enzyme responsible for pigment production is more sensitive to heat than others in the animal cells and unfoldsin the cooler environment of the extremities
C) the enzyme responsible for pigment production is more sensitive to cold than others in the animal cells and maintains activity in the cooler environment of the extremities
D) the enzyme responsible for pigment production is more sensitive to heat than others in the animal cells and maintains activity in the cooler environment of the extremities