Final answer:
The most appropriate next step in the management of this patient is dietary avoidance of wheat, barley, and oats. The clinical presentation and laboratory evaluation suggest celiac disease, which is an autoimmune disorder triggered by gluten consumption. The gold standard for diagnosis is endoscopy and biopsy, but serological tests can be used as screening tools.
Step-by-step explanation:
The most appropriate next step in the management of this patient is B. Dietary avoidance of wheat, barley and oats. The clinical presentation, including chronic diarrhea, foul-smelling and greasy stools, and weight loss, along with the presence of elevated serum anti-tissue transglutaminase (anti-TTG) antibodies, suggests celiac disease. Celiac disease is an autoimmune disorder triggered by the consumption of gluten. The gold standard for diagnosis is endoscopy and biopsy of the duodenal mucosa, but serological tests can be used as screening tools. The most effective treatment for celiac disease is strict adherence to a gluten-free diet.