Read the dialogue and answer the question.

Source: youtube.com

Yesterday at school.

Teacher: What's the matter with you, Fred?
Fred: I have a stomachache.
Teacher: Did you eat this morning?
Fred: Just some candies.
Teacher: You should have lunch soon. Go to the canteen. It is twelve o'clock already.
Fred: OK, Mam. Thank you.

Which part of Fred's body that hurts?