Please help with explanations

2.1 Explain what is meant by the concept of urban sprawl. [4 points] 2.2 What are the costs and benefits of urban sprawl from the perspective of urban residents and the environment? Explain. [4 points] 2.3 According to Zheng et al. (2011), do Chinese cities pollute as much as U.S. cities today? Why or why not? How might an increase in sprawl in Chinese cities change this relationship? [2 points]