Concept:Non-renewable energy sources are those that cannot be replaced or regenerated once they are used up.
Explanation:Petroleum is formed over millions of years from the remains of dead organisms under high pressure and heat.
This natural process is extremely slow when compared to the rate at which petroleum is consumed by humans.
Once a petroleum reserve is extracted and burnt, it cannot be restored within a useful time span.
Petroleum is not recycled after use, and it cannot be manufactured quickly.
Therefore, it is classified as a non-renewable source of energy because it cannot be regenerated after it is used up.
Answer:D. cannot be regenerated once used up