Since the first Earth Day in 1970, Americans have gotten a lot "greener" toward the environment . "We didn't know at that time there even was an environment, let alone that there was a problem with it," says Bruce Anderson, president of Earth Day USA. But what began as nothing important in public affairs has grown into a social movement. Business people, political leaders, university professors, and especially millions of grass-roots Americans are taking part in the movement. "The understanding has increased many, many times," says Gaylord Nelson, the former governor from Wisconsin, who thought up the first Earth Day.  According to US government reports, emissions from cars and trucks have dropped from 10.3 million tons a year to 5.5 tons .The number of cities producing CO beyond the standard has been reduced from 40 to 9 .Although serious problems still remain and need to be dealt with , the world is a safer and healthier place .A kind of "Green thinking " has become part of practices . Great improvement has been achieved .In 1988 there were only 600 recycling programs; today in 1995 there are about 6,600 .Advanced lights ,motors , and building designs have helped save a lot of energy and therefore prevented pollution . Twenty -five years ago , there were hardly any education programs for environment .Today , it's hard to find a public school , university , or law school that does not have such a kind of program ." Until we do that, nothing else will change! " say Bruce Anderson. Where does the support for environmental protection mainly come from?
The grass -roots level The business circle Government officials University professors
Question: Since the first Earth Day in 1970, Americans have gotten a lot "greener" toward the environment . "We didn't know at that time there even was an environment, let alone that there was a problem with it," says Bruce Anderson, president of Earth Day USA. But what began as nothing important in public affairs has grown into a social movement. Business people, political leaders, university professors, and especially millions of grass-roots Americans are taking part in the movement. "The understanding has increased many, many times," says Gaylord Nelson, the former governor from Wisconsin, who thought up the first Earth Day.  According to US government reports, emissions from cars and trucks have dropped from 10.3 million tons a year to 5.5 tons .The number of cities producing CO beyond the standard has been reduced from 40 to 9 .Although serious problems still remain and need to be dealt with , the world is a safer and healthier place .A kind of "Green thinking " has become part of practices . Great improvement has been achieved .In 1988 there were only 600 recycling programs; today in 1995 there are about 6,600 .Advanced lights ,motors , and building designs have helped save a lot of energy and therefore prevented pollution . Twenty -five years ago , there were hardly any education programs for environment .Today , it's hard to find a public school , university , or law school that does not have such a kind of program ." Until we do that, nothing else will change! " say Bruce Anderson. Where does the support for environmental protection mainly come from?
A. The grass -roots level
B. The business circle
C. Government officials
D. University professors
Answer: