Christiaan Barnard is famous for:

performing the world's first human heart transplant

The correct answer is Option (2) - performing the world's first human heart transplant

Christiaan Barnard, a South African surgeon, gained worldwide acclaim for performing the world's first successful human heart transplant surgery on December 3, 1967. The groundbreaking procedure took place at Groote Schuur Hospital in Cape Town, South Africa. Barnard and his team transplanted the heart of a deceased donor into the chest of Louis Washkansky, a 53-year-old patient suffering from heart failure. The surgery marked a significant milestone in medical history, demonstrating the feasibility of organ transplantation and offering hope to patients with end-stage heart disease. Barnard's pioneering work revolutionized the field of cardiac surgery and paved the way for further advancements in organ transplantation.