Cholesterol Metabolism & Lipoprotein Disorders — Practice

A 35-year-old man with recurrent acute pancreatitis has fasting plasma that is creamy with a supranatant layer on standing overnight; triglycerides exceed 2000 mg/dL but cholesterol is near normal, with onset in adulthood. Which apolipoprotein deficiency best explains failure of lipoprotein-lipase activation?