Which of the following is not a noncommercial food service operation?

hotel dining room

school dining hall

hospital cafeteria

ballpark hot dog vendor

Ballpark hot dog vendor

is most probably outside of the park (in the sense that it could be external stand) and it's purpose is making a profit

whereas

hotel: look to provide service

hospital: make it more pleasant/easier for doctors or family members

school dinning hall: is required and necessary for children

ballpark hot dog vendor