Solar energy for your home is coming. It can help you as a single home owner. It can help the whole country as well. Whether or not solar energy can save your money depends on many things. Where you live is one factor and the type of home you have is another. Things like insulation  , present energy costs, and the type of system you buy are added factors. Using solar energy can help save our precious fuel. As you know, our supplies of oil and gas are very limited. There is just not enough on hand to meet all our future energy needs. Sooner or later Mother Nature will say that's all. The only way we can delay hearing those words is by starting to save energy now and by using other sources, like the sun. We won't have to worry about the sun's running out of energy for another several billion years or so. Besides, the sun doesn't offer as many problems as other energy sources. For example, fossil fuel  adds to already high pollution levels. With solar energy, we will still need sources of energy, but we won't need as much. That means we can cut down on our pollution problems. With all these good points, why don't we use more solar power? There are many reasons for this. The biggest reason is money. Until now, it was just not practical for a home owner to put in a solar unit. There were cheaper sources of energy. All that is changing now. Solar costs are starting to equal the costs of oil and electricity. Experts say that gas, oil and electricity prices will continue to rise. The demand for electricity is increasing rapidly. But new power plants will use more gas, oil or coal. Already in some places the supply of electricity is being rationed  . Solar energy is now in its infancy  . It could soon grow to become a major part of our nation's energy supply. The sun is an endless source of energy, and it will not run out of energy for   _  .
several million years several hundred years several billion years several thousand years
Question: Solar energy for your home is coming. It can help you as a single home owner. It can help the whole country as well. Whether or not solar energy can save your money depends on many things. Where you live is one factor and the type of home you have is another. Things like insulation  , present energy costs, and the type of system you buy are added factors. Using solar energy can help save our precious fuel. As you know, our supplies of oil and gas are very limited. There is just not enough on hand to meet all our future energy needs. Sooner or later Mother Nature will say that's all. The only way we can delay hearing those words is by starting to save energy now and by using other sources, like the sun. We won't have to worry about the sun's running out of energy for another several billion years or so. Besides, the sun doesn't offer as many problems as other energy sources. For example, fossil fuel  adds to already high pollution levels. With solar energy, we will still need sources of energy, but we won't need as much. That means we can cut down on our pollution problems. With all these good points, why don't we use more solar power? There are many reasons for this. The biggest reason is money. Until now, it was just not practical for a home owner to put in a solar unit. There were cheaper sources of energy. All that is changing now. Solar costs are starting to equal the costs of oil and electricity. Experts say that gas, oil and electricity prices will continue to rise. The demand for electricity is increasing rapidly. But new power plants will use more gas, oil or coal. Already in some places the supply of electricity is being rationed  . Solar energy is now in its infancy  . It could soon grow to become a major part of our nation's energy supply. The sun is an endless source of energy, and it will not run out of energy for   _  .
A. several million years
B. several hundred years
C. several billion years
D. several thousand years
Answer: