Question :Researchers like Robert Constanza et.al., have put an average price tag of US$_____ trillion a year on the fundamental ecological services

Question :Researchers like Robert Constanza et.al., have put an averag

1.	Question :Researchers like Robert Constanza et.al., have put an average price tag of US$_____ trillion a year on the fundamental ecological services
Answer» 33 50 6 18 Answer :A