The correct answer is the following.
There are two main challenges that metropolitan areas are facing today: excessive population and air and water pollution.
These two issues keep authorities and people worried because are affecting people in great metropolitan areas such as Los Angeles, New York-New Jersey, Chicago, Atlanta, Dallas-Forth Worth Area, and many other large cities. And this is an international issue because worldwide the problem is major. Cities such as Mexico City, Buenos Aires, Sau Paulo, Madrid, among others, suffer from the same challenges.
Governmental officials are trying to attack these issues with programs that limit the use of cars or have cars engines tested on a six-month basis. They are investing in better transportation and the use of electric cars. Some others are building more subway lines to invite people not to use cars.
In other cases, governments are trying to invest in better infrastructure in the former cities of people to stop emigration lo larges cities. Officials think that if there are jobs and industry in their former cities, people would stop emigration.
Finally, there are many campaigns inviting citizens to pay attention and limit the use of water and totally avoid any waste of the precious liquid. In cities such as Mexico City, the government has ordered the cut of water service during weekends in order to replenish water stations.
