Which of the following microorganism causes 'Buruli ulcer'?

Buruli ulcers are rapidly growing ulcers caused by the acid-fast bacillus, Mycobacterium ulcerans. After leprosy and tuberculosis, this ulcer is the third most common mycobacteriosis of immunocompetent hosts in tropical and subtropical wetlands. It is a painless ulcer has a deep necrotic base and undermined edges. Regional lymphadenopathy and systemic symptoms are minimal to absent. Without treatment, ulcers may spontaneously heal within 6 to 9 months, or they may spread rapidly, causing extensive deformity. Surgical excision is the treatment of choice. Antimycobacterial treatment is often ineffective. Ref: Morrell D.S. (2011). Chapter 247. Disorders of the Hands, Feet, and Extremities. In J.E. Tintinalli, J.S. Stapczynski, D.M. Cline, O.J. Ma, R.K. Cydulka, G.D. Meckler (Eds), Tintinalli's Emergency Medicine: A Comprehensive Study Guide, 7e.