Final answer:
The factor that kept Morgan coming back for more food during his 30-day McDonald's challenge was the convenience of McDonald's.
Step-by-step explanation:
The factor that kept Morgan coming back for more food during his 30-day McDonald's challenge was B) The convenience of McDonald's.
Convenience is a major factor that attracts people to fast food, especially when they are busy or under pressure. McDonald's, being a fast food chain, offers quick and easy meals that can be easily accessible through drive-through windows.