This patient is showing the symptoms of disaccharide intolerance (Lactose, Sucrose, Maltose). Most likely it is lactase deficiency. But it is not given in the options. So the answer goes to Sucrase. A disaccharide intolerance is a manifestation of carbohydrate malabsorption. In most people, lactase is gradually lost through adolescence, leading to lactose intolerance. Ref: Harper's Biochemistry, 26th Edition, Page 475 ; Wheat-Free, Worry-Free By Danna Korn, 2002