According to the author, the primary solution to environmental problems is （    ）。

(单选题)I don’t like ( ) bills but when I do get them I like ( (单选题)Fred entered without knocking and, very out of breath, sank (单选题)He wasn’t asked to take on the chairmanship of the society, (单选题)I think he is taking an active part in social work. I agree (单选题)We realized that he was under great ( ), so we took no no (单选题)I hope my school life of senior high will be ( ) than tha (单选题)After the new technique was introduced, the factory produced (单选题)She ( ) fifty or so when I first met her at a conference. (单选题)I ( ) writing the paper as scheduled, but my mother’s ill (单选题)She is the only one among the ( ) writers who ( ) stor