原题
Green Roof Benefits
Green roofs, or living roofs, are gaining prominence in urban areas due to their environmental benefits. These are roofs covered with vegetation to help manage stormwater by absorbing rainfall, decreasing runoff, and minimizing flooding risks.
Another advantage of green roofs is their ability to improve air quality. Plants on the roof filter pollutants and capture dust. Additionally, green roofs reduce the urban heat island effect. Conventional roofs absorb and radiate heat, increasing urban temperatures. In contrast, green roofs keep buildings cooler by providing insulation and emitting moisture through their plants and soil.
Green roofs offer energy-efficiency benefits. The insulation provided by soil and plants reduces the need for heating in winter and cooling in summer, leading to energy savings. Green roofs can also extend the lifespan of the roof by shielding materials from UV radiation and extreme temperatures, keeping the underlying structure sound for longer.
Finally, green roofs support urban biodiversity. Their vegetative layers create habitats for insects and birds in cities where green spaces are limited. These microhabitats help sustain pollinator populations and promote ecological balance. Green roofs can even be designed to grow food, contributing to food security in urban environments.
Despite these advantages, green roofs can be costly to install. However, many cities offer incentives to encourage their adoption.
Why does the author mention vegetative layers?
ATo support the claim that pollinator populations in cities are increasing
BTo show how insect and bird populations can be supported by green roofs
CTo discuss one potential way to provide access to food for urban residents
DTo address the concern that green roofs may be too costly to maintain
正确答案：B
解题思路
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