What are the four etiologies of mesenteric ischemia? Most common first.
a) Atherosclerosis, embolism, thrombosis, non-occlusive
b) Embolism, non-occlusive, thrombosis, atherosclerosis
c) Thrombosis, embolism, atherosclerosis, non-occlusive
d) Non-occlusive, atherosclerosis, thrombosis, embolism