What diagnosis for abdominal pain best describes his symptoms and signs?

A 76-year-old retired farmer comes to your office complaining of abdominal pain, constipation, and a low-grade fever for about 3 days. He denies any nausea, vomiting, or diarrhea. The only unusual thing he remembers eating is two bags of popcorn at the movies with his grandson, 3 days before his symptoms began. He denies any other recent illnesses. His past medical history is significant for coronary artery disease and high blood pressure. He has been married for over 50 years. He denies any tobacco, alcohol, or drug use. His mother died of colon cancer and his father had a stroke. On examination he appears his stated age and is in no acute distress. His temperature is 100.9 degrees and his other vital signs are unremarkable. His head, cardiac, and pulmonary examinations are normal. He has normal bowel sounds and is tender over the left lower quadrant. He has no rebound or guarding. His rectal examination is unremarkable and his fecal occult blood test is negative. His prostate is slightly enlarged but his testicular, penile, and inguinal examinations are all normal. Blood work is pending.

What diagnosis for abdominal pain best describes his symptoms and signs?

A) Acute diverticulitis
B) Acute cholecystitis
C) Acute appendicitis
D) Mesenteric ischemia