Teeth break food into small pieces. Throat muscles push food toward the stomach. Stomach acids dissolve food into nutrients. Intestinal cells transport nutrients into the blood.
I am hesitating between 4 options to answer the following question, which option should I choose?
Question: Which part of digestion is mainly a chemical change?
Possibilities:
- Teeth break food into small pieces.
- Throat muscles push food toward the stomach.
- Stomach acids dissolve food into nutrients.
- Intestinal cells transport nutrients into the blood.

Stomach acids dissolve food into nutrients.