How could renewable energy sources be used to power a car? what renewable sources of energy are available? which renewable sources could be used to operate the car? how could each source be used? what equipment would be needed? where would this equipment be located? what backup systems should be included?

There are many ways renewable energy can power a car. The most popular renewable energy that powers cars are electric cars. They run on battery and need to be charged. They are very eco-friendly and don't produce as many greenhouse gases. There are also some cars that run on solar energy which is energy from the sun. 

For the electric car, an electric motor would be needed also a large battery. 
For the solar-powered car, you would need solar panel and the sun's energy. 

The electric car would need charging to be on the road for long. 
The solar-powered car would need backup when the sun goes down. 

The answer is probably c. xylem