Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the following questions from 46 to 50. These days, power is a big concern for many countries. People are using more and more electricity, but our traditional sources of electricity, coal and oil are limited. In addition, both coal and oil power plants create a lot of pollution. How will we get enough electricity in the future? Some scientists are looking to the sky for ...

Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the following questions from 46 to 50.

These days, power is a big concern for many countries. People are using more and more electricity, but our traditional sources of electricity, coal and oil are limited. In addition, both coal and oil power plants create a lot of pollution. How will we get enough electricity in the future? Some scientists are looking to the sky for answers.

The sun is an almost endless source of energy. Every minute, the earth gets enough energy from the sun to provide the world with electricity for a year. The problem is that this energy is in the form of heat and light. To use solar energy, we need to change it into electricity. Solar cells already do this for calculators and other electronics. Unfortunately, solar cells only produce a small amount of electricity. We can make larger solar cells, but it is very expensive,

Instead, scientists are now trying to build more solar power plants. These power plants use thousands of huge mirrors to focus the light of the sun on a small place where it creates a lot of heat. The heat will then be used to create electricity. This creates more electricity than solar cells, but not enough. The biggest solar power plant in the world creates 15 megawatts of electricity. In contrast, most nuclear power plants create about 1,000 megawatts of electricity.

Which can be the best title for the passage?