What is a key aspect of the normal anatomy and physiology of the gastrointestinal system?
a. Continuous movement of food through the digestive tract
b. Frequent retention of food in the stomach
c. Infrequent production of digestive enzymes
d. Irregular absorption of nutrients in the intestines

Which population may exhibit normal variations in the gastrointestinal system?
a. Older adults
b. Infants
c. Adolescents
d. Young adults