The substance that contains enzymes that break down food after it enters the mouth is C. saliva.
Here's why:
1. Saliva is produced by the salivary glands in the mouth.
2. Saliva contains an enzyme called amylase which helps break down carbohydrates in the food we eat into smaller molecules like sugars.
3. Once food is chewed and mixed with saliva in the mouth, amylase starts the process of breaking down the carbohydrates present in the food.
4. This breakdown of carbohydrates into simpler sugars by amylase in saliva is the first step in the digestion process before the food moves down the esophagus into the stomach.
Therefore, the correct answer is C. saliva.
