Chlorella was first used in photosynthesis by:

Correct option is C

✅ (c) Warburg: • Otto Warburg first used Chlorella to study the rate of photosynthesis under different conditions. • His work laid the foundation for understanding the photosynthetic process and gas exchange.
❌ (a) Calvin: • Known for discovering the Calvin cycle, but did not first use Chlorella.
❌ (b) Hill: • Known for the Hill reaction related to oxygen evolution.
❌ (d) Ruben: • Worked on isotopic tracing, not the first use of Chlorella.