Fact 1: Digestion is the process of breaking down food into components the body can absorb.

Fact 2: Saliva starts to break down the food.

Given the two facts above, answer the question "what does digestion involve?" with the following options: 
- ovaries
 - saliva
 - Energy.
 - chemicals
 - heat
 - cooking
 - cooking food
 - matter


 

  saliva       