Today, in our environmental science lecture, we will discuss the impact of urban farming on local ecosystems. One key point is that rooftop gardens can significantly reduce the heat island effect in cities. However, they also require careful water management to avoid runoff issues. For example, a study in Chicago showed that green roofs retained about 60% of rainfall, but only when the soil depth was at least 15 centimeters. Additionally, these gardens provide habitats for pollinators like bees, but they may attract unwanted pests if not maintained properly. So, while urban farming offers benefits, its success depends on design and maintenance.
❓ According to the lecture, what condition is necessary for a green roof to retain 60% of rainfall?
A. A. The roof must be located in a warm climate
B. B. The soil depth must be at least 15 centimeters
C. C. The garden must include native plant species