The author use the word "grassroots" ( Line 1, Para. 2 ) to mean _______.

A．call on the people to go on street for a better proposal
B．let the public catch onto more new ideas
C．show that we can do something for the environment
D．arouse our anger for the destruction of nature

A．They provide only suggestions and ideals but never put them into practice.
B．People need pay more attention to the knowledge of environment preservation.
C．Desperate pollution in many areas is to deprive mankind of a good future.
D．Survival of mankind pivots on their ability to find new resources.