Which of the following contributes to food spoilage?

Exposure to air and moisture significantly contributes to food spoilage because it creates an environment conducive to the growth of bacteria, molds, and yeasts, all of which can lead to the deterioration of food quality. When food is exposed to air, oxygen can promote oxidation, causing changes in flavor, color, and texture. Moisture can facilitate microbial growth, causing the food to spoil faster. Ensuring food is properly sealed helps minimize exposure to these factors, thus reducing spoilage.

The other options, such as proper sealing and optimal temperatures, actually help in preserving food. Proper sealing reduces the contact with air and moisture, while maintaining optimal temperatures slows down the growth of spoilage organisms. Reduced light exposure is also beneficial, as light can degrade certain nutrients in food and promote spoilage in some cases.