A、Fossil fuels. B、Nuclear power stations. C、Wind turbines. D、Solar panels. A原文中男士提到，现在人类消耗的大多数能源——86％——来自化石燃料。因此答案为A。

W: Good evening. Welcome to our TV show Life in the Future. Today, our honored guest is Mr. Smith from the University of Kentucky. Our topic today is what our future will be like in the next 100 years.
M: Good evening. In fact, I’d like to share my views on this topic through several numbers. The first number is about how the world’s population will continue to increase.
W: I guess we will experience another population explosion in the next 30 years.
M: Well, there will be 11. 2 billion of us by 2100, according to the UN’s most likely scenario. But this is a projection, not a certainty. There’s an outside chance the world’s population could be as high as 16. 6 billion by the end of the century. Or it could be as low as 7. 3 billion—that’s fewer people than the 7. 5 billion alive today. In all the UN scenarios, though, the population keeps increasing until at least 2050.
W: How about the average age?
M: It will be steadily rising because we’re living longer and having fewer children each. Today, the average global life expectancy is nearly 72 years and by 2100 it is projected to increase to over 83 years.
W: Longer lives mean more old people, while lower fertility rates mean relatively fewer people are born to replace them—the so-called population pyramid is turning into a beehive. Where will we be living then?
M: By 2030, there will be 41 megacities of more than 10 million people. And by 2050, two-thirds of us will live in urban areas. Super-dense cities could house everyone on a surprisingly small amount of land.
W: The last question is where the world’s energy will come from?
M: Today, the vast majority of the energy humanity consumes—86％—comes from fossil fuels. Renewable energy sources account for around 10％ of the total, but that share is growing fast. Global solar energy consumption was around 7. 5 times higher in 2015 than 2010. In a future dominated by renewables, countries with lots of land on which to site wind turbines and solar panels could find themselves at a distinct advantage.
Questions 5 to 8 are based on the conversation you have just heard.
5. What is the woman’s prediction of the population in the future?
6. What makes the average age rise steadily?
7. What will the structure of population be like in the future?
8. Where does most of the energy humanity consumes come from nowadays?