Final answer:
The key factor in monitoring refrigerated food is maintaining the correct temperature to prevent bacterial growth and ensure food safety.
Step-by-step explanation:
The most important factor in monitoring food stored under refrigeration is C. Temperature. Consistent, appropriate temperatures are essential for preventing bacterial growth and maintaining food safety. Visual cues like color and texture changes, or sensory cues like smell, can indicate spoilage, but they do not prevent it. Maintaining the correct temperature slows down the growth of bacteria and preserves the food's quality. While all the factors such as color, smell, and texture can provide signs of food quality, they are secondary compared to the critical role of temperature control in refrigeration.