The first heart transplant was performed by
Christiaan Barnard
The correct option is (D)
Explanation of the correct option:
Christiaan Barnard performed the first heart transplant surgery ever in the world.
Explanation of the incorrect options:
Option A
James Watson discovered the molecular structure of DNA.
Option B
William Harvey discovered details about blood circulation.
Option C
Har Gobind Khurana constructed the first synthetic gene.
Final answer: First heart transplant was performed by Christiaan Barnard.