Which correctly lists the digestive system careers from the least amount of formal education to the most?

An endoscopy technician typically needs the least formal education, usually a certificate or associate degree. An orthodontist must first complete dental school and then specialized orthodontic training, while a gastroenterologist completes medical school and several years of specialty training. So the order from least to most education is endoscopy technician, orthodontist, gastroenterologist, which is choice D.

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