The correct answer is (a) Koppen.
Wladimir Köppen (1846-1940) was a German-Russian climatologist and meteorologist. He is best known for his climate classification system, which is still widely used today. Köppen’s system is based on the relationship between climate and vegetation. He believed that vegetation was the best indicator of climate because it is directly affected by temperature, precipitation, and other climatic factors.
The other options are incorrect.
(b) Stamp was a British geographer who is best known for his work on land use and agricultural geography.
(c) Thornthwaite was an American climatologist who is best known for his work on the water balance and evapotranspiration.
(d) Koteshwaram is an Indian meteorologist who is best known for his work on monsoons.