Select the correct text in the passage.
An environmentalist delivered a speech about how young people are unwilling to conserve natural resources. Which sentence in the passage contains the persuasive technique of expert opinion?
Teens and Conversion Trends
An Inconvenient Truth, Al Gore's movie on global warming, is now the fourth highest-grossing documentary of all time. But apparently, it isn't young adults who are paying the price of the ticket or, more important, taking the truth about the environment to heart.

In fact, the inconvenient truth today is that youths' willingness to conserve gas, heat, and energy has taken a steep plunge since the 1980s. According to data from Monitoring the Future, a federally funded national survey on trends in the attitudes, values, and behavior of high school seniors since 1976, there has been a clear decline in conservation behavior among 18-year-olds over the past 27 years; although, we are not yet sure whether these attitudes follow youths into adulthood. One of every fifteen teens participates in conservation. Compare that to one in five during the 1970s. This decline, interestingly, is coupled with a rise in materialistic values.

In fact, trends in materialism and conservation are highly related. At times when youths place higher value on material goods, they are also much less likely to say they would conserve resources. And when youths are more materially driven, they are also less likely to believe that natural resources will become scarce in the future. Since the 1990s, the trends in materialism seem to have topped out at a steady high level. The willingness to conserve keeps declining. These opposing values should raise a red flag about the consumer culture and its influence on youth.