The correct answer for this question is option 3: Maximum biodiversity.

Tropical rainforests are known for their high levels of biodiversity, meaning they have a wide variety of different plant and animal species. These forests are home to countless species of plants, birds, mammals, insects, and other organisms. The abundance of different species and their interactions contribute to the complex and intricate ecosystems found in tropical rainforests.

Options 1, 2, and 4 are incorrect. Tropical rainforests are not characterized by the absence of trees (option 1) as they are, in fact, densely populated with tall and broadleaf evergreen trees. They also have high productivity (option 2) due to the nutrient-rich soils and warm climate, which supports the growth of a wide range of plants and organisms. Lastly, tropical rainforests have maximum rather than minimum biodiversity (option 4), as previously mentioned.