The correct answer is option 1: Tropical rain forests.
Cinchona trees, which are the source of the drug quinine, grow naturally in tropical rain forests. Tropical rain forests are characterized by a hot and humid climate with high levels of rainfall throughout the year. These forests are typically found in regions near the equator, such as the Amazon rainforest in South America and the Congo Basin in Africa.
Cinchona trees require specific environmental conditions to thrive, which are commonly found in tropical rain forests. These conditions include high humidity, warm temperatures, and consistent rainfall. The dense canopy of the rainforest provides shade and protection for the Cinchona trees, allowing them to grow and reproduce.
Quinine, derived from the bark of Cinchona trees, is known for its medicinal properties and is used to treat malaria. The presence of Cinchona trees in tropical rain forests is vital for the production of quinine and for the preservation of biodiversity in these unique ecosystems.
In summary, Cinchona trees, the source of quinine, grow naturally in tropical rain forests due to the specific environmental conditions provided by these ecosystems.