Final answer:
The most likely anatomic location of the 81-year-old man's pathology is the inferior mesenteric artery (c).
Step-by-step explanation:
An 81-year-old man with a history of atrial fibrillation presents with abdominal pain. Considering his age and medical history, the most likely site of pathology associated with such pain is the superior mesenteric artery (SMA). The SMA supplies blood to a majority of the small intestine as well as portions of the large intestine. Given that atrial fibrillation increases the risk of clot formation, which can lead to ischemia if a clot lodges in the SMA, mesenteric ischemia is a strong consideration for abdominal pain in this patient demographic.
The most likely anatomic location of the 81-year-old man's pathology is the inferior mesenteric artery (c). The inferior mesenteric artery is one of the branches that arise from the abdominal aorta and supplies blood to the distal segment of the large intestine, which includes the rectum. Given the patient's age and history of atrial fibrillation, it is possible that the abdominal pain is due to ischemia or reduced blood flow to the large intestine, which can be caused by conditions such as embolism or thrombosis in the inferior mesenteric artery.