Lower extremity ulcers venous stasis arterial ischemic and neuropathic

A 62-year-old man with poorly controlled diabetes presents to the clinic with a painless ulcer beneath the first metatarsal head. The ulcer displays a dark red base and well-defined calloused edges. Which of the following is the most likely cause of this ulcer?

1: Venous stasis ulcer
2: Arterial ischemic ulcer
3: Neuropathic ulcer from diabetes
4: Buerger's disease