A 36-year-old woman presents with 6 months of chronic diarrh…

A 36-year-old woman presents with 6 months of chronic diarrhea and weight loss. She reports bulky, foul-smelling stools that are difficult to flush. Her symptoms improve slightly when fasting but do not completely resolve. She has a history of chronic pancreatitis related to alcohol use. Stool studies show: Stool sodium: 50 mEq/L Stool potassium: 30 mEq/L Which of the following is the most likely underlying mechanism of this patient’s diarrhea?