Problem: A 74-year-old man complains of epigastric discomfort. There is no jaundice evident, but an enlarged gallbladder is palpated. The bilirubin level is 13 mg/dL, the alkaline phosphatase level is 410 U, and the hematocrit is 35 percent. CT scan dilated gall bladder. What is the most likely malignant tumor causing extrahepatic obstructive jaundice? Select one: a. Gallbladder b. Common hepatic duct c. Head of the pancreas d. Periampullary area