Who proposed the principle of photosynthesis?

The correct answer is Option (3) → Melvin Calvin

The American chemist Melvin Calvin, working with radioactive carbon-14 in the 1940s and 1950s, traced the path by which plants turn carbon dioxide into sugar during photosynthesis. This series of dark (light-independent) reactions is called the Calvin cycle, and it won him the Nobel Prize in Chemistry in 1961.