Which of these sentences is an opinion?
A) A great problem with our society is a lack of understanding of the contributions that using renewable energy can have.


B) Wind, solar, and hydropower are examples of renewable energy sources.


C) Non-renewable energy sources, such as petroleum, natural gas, and coal make up over eighty percent of the nation's energy consumption.


D) Technological advances have made it possible for solar energy to work even when it is cloudy or during the night.