The main source of air pollution in Japan is in- dustry. Recently, a rise in the number of motor vehicles using petroleum fuel has caused pollution from exhaust gases to be- come increasingly important. (According to the web)
Answer:
The description corresponds to an observational study.
Explanation:
In Observational studies, researchers observe the effect of a risk factor without changing what is exposed to it or its conditions. On the other hand, in an experimental study, researchers can introduce a change and study the effects of it.
Today's world population growth compared to the population growth 100 years ago is a big, big difference. The population has doubled many, many times, and even right now the world's population is still skyrocketing. There are several reasons for this. There have been scientific advances in health and medicine. Governments are providing cleaner public drinking water and more sanitary waste removal. With this, people are less likely to get sick. Another reason for rapid population growth is agriculture. Scientists have created newer, better methods to increase the world's food supply, and to make it healthier. They have created method's to protect crops from harmful insects, and to raise crops with less water. This is called the Green Revolution.
Federalism is a compromise meant to eliminate the disadvantages of both systems. In a federal system, power is shared by the national and state governments. The Constitution designates certain powers to be the domain of a central government, and others are specifically reserved to the state governments.
