<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A 67-year-old man presents to his primary care physician with constant and gnawing lower abdominal pain for 2 days. The pain has been steadily worsening in intensity. He says the pain occasionally radiates to his lower back and groin bilaterally. While he cannot identify any aggravating factors, he feels that the pain improves with his knees flexed. His medical history is notable for hypertension which is well controlled with medications. He has smoked 4050 cigarettes daily for 35 years. On examination, there is a palpable pulsatile mass just left of midline below the umbilicus. He is immediately referred for definitive management but during transfer, he becomes hypotensive and unresponsive. Which of the following is the most likely diagnosis?? A: Diverticulitis, B: Gastrointestinal hemorrhage, C: Ruptured abdominal aortic aneurysm, D: Appendicitis, E: Irritable bowel syndrome,  <response>: Based on the description of a 67-year-old man with constant and worsening lower abdominal pain that radiates to the back and groin bilaterally, a history of smoking, and a palpable pulsatile abdominal mass, the most likely diagnosis is a ruptured abdominal aortic aneurysm. Diverticulitis, GI hemorrhage, appendicitis, and IBS are less likely based on the clinical presentation. The key findings pointing to a ruptured AAA are the age, smoking history, pulsatile abdominal mass, and sudden hypotension.C: Ruptured abdominal aortic aneurysm 