What does the author's attitude toward recycling solid waste

A．requires further research
B．is available now
C．remains to be developed
D．is still being experimented

A．American people realize that all the wastes can be converted into useful resources
B．the main barrier for recycling is the lack of valuable new technological approaches
C．today only a little of the waste is diverted from municipal dump due to the high cost
D．it is much more cheaper to use recycled materials