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 questions

In this era of increased global warming and diminishing fossil fuel supplies, we must begin to put a greater priority on harnessing alternative energy sources. Fortunately, there are a number of readily available, renewable resources that are both cost- effective and earth – friendly. Two such resources are solar power and geothermal power

Solar energy, which reaches the earth through sunlight, is so abundant that it could meet the needs of worldwide energy consumption 6,000 times over. And solar energy is easily harnessed through the use of photovoltaic cells that convert sunlight to electricity. In theUSalone, more than 100, 000 homes are equipped with solar electric systems in the form of solar panels or solar roof tiles. And in other parts of the world, including many developing countries, the use of solar system is growing steadily

Another alternative energy source, which is abundant in specific geographical areas, is geothermal power, which creates energy by tapping heat from below the surface of the earth. Hot water and steam that are trapped in underground pools are pumped to the surface and used to run a generator, which is produces electricity. Geothermal energy is 50, 000 times more abundant than the entire known supply of fossil fuel resources. And as with solar power, the technology needed to utilize geothermal energy is fairly simple. A prime example of effective geothermal use inIceland, a region of high geothermal activity where over 80 percent of private homes are heated by geothermal power.

Solar and geothermal energy are  just two of promising renewable alternatives to conventional energy sources. The time is long overdue to invest in the development and use of alternative energy on global scale

According to the passage, why should we consider using alternative energy sources ?