A 28 year old man presents with diarrhea, fecal urgency, and weight loss. His stool is malodorous and is difficult to flush. He also reports pain and stiffness and in his elbows and knees. Sigmoidoscopy reveals discontinuous lesions and granulomas. No blood is detected in the stool. This is most consistent with which diagnosis would his care team first suspect?

A. Crohn disease
B. Ulcerative colitis
C. Diverticulitis
D. Colon cancer