Final answer:
The key dietary factor that relates to dental caries is sugar consumption. Sugary foods and drinks can cause tooth decay by producing acids that dissolve the minerals in the teeth.
Step-by-step explanation:
The key dietary factor that relates to dental caries is sugar consumption. When sugary foods and drinks are consumed, the bacteria in the mouth break down the sugars and produce acids that can dissolve the minerals in the teeth, leading to tooth decay. Reducing sugar consumption and practicing good dental hygiene are important for preventing dental caries.