Answer: B. This procedure begins with the surgeon removing a large part of the stomach. The valve that releases food to the small intestine remains, along with the duodenum. The surgeon then closes off the middle section of the intestine and attaches the last part directly to the duodenum. This is the duodenal switch. The separated section of the intestine is not removed from the body. Instead, it is reattached to the end of the intestine, allowing bile and pancreatic digestive juices to flow into this part of the intestine. This is the biliopancreatic diversion. As a result of these changes, food bypasses most of the small intestine, limiting the absorption of calories and nutrients. The patient in this study stopped taking his recommended twice-daily multivitamins, twice-daily calcium, and vitamin B12, and as a result, several of his vitamin levels were deficient.