teeth in the mouth saliva in the mouth enzymes in the stomach enzymes in the small intestine
I gave my students this multiple choice question: What part of the digestive system first causes chemical changes to food?

Only one answer is correct among these 4 choices:
- teeth in the mouth
- saliva in the mouth
- enzymes in the stomach
- enzymes in the small intestine

Could you tell me which one is correct?

saliva in the mouth