The last sentence of the text shows thatA．Van Oss has full confidence in the developers an

The last sentence of the text shows that

A．Van Oss has full confidence in the developers and the public in using new concrete.

B．Van Oss is pessimistic about the future development of greener concrete.

C．Van Oss is hostile to the attitudes of developers and the public.

D．Van Oss feels that people should be patient to wait for the change of the public attitude.