Step 1: Concept
Alkaloids are naturally occurring organic nitrogen-containing compounds found in plants that often have potent pharmacological effects.
Step 2: Meaning
Cinchona refers to a genus of flowering plants in the family Rubiaceae, native to the Andes forests of western South America.
Step 3: Analysis
Morphine is derived from the poppy plant; Cocaine comes from coca leaves; Reserpine is extracted from Rauwolfia serpentina. Quinine is the famous alkaloid extracted from the bark of the Cinchona tree.
Step 4: Conclusion
Quinine has been historically used as a primary treatment for malaria, making it the correct alkaloid associated with Cinchona bark.
Final Answer: (B)