This passage is mainly about _____.

A．is the only agency studying the effects of air pollution on health
B．has launched a surprised attack on researchers
C．has decided to decrease the permitted concentration of airborne dust
D．has tremendously improved pollution control

A．They stressed photography was a means of making people happy.
B．It was art for recording the world.
C．It was a device for observing the world impartially.
D．It was an art comparable to painting.

A．He wants to provide an example of artists who, like serious contemporary photographers, disavowed traditionally accepted aims of modem art.
B．Be wants to set forth an analogy between the Abstract Expressionist painters and classical Modernist painters.
C．He wants to provide a contrast to Pop artist and others.
D．He wants to provide an explanation of why serious photography, like other contemporary visual forms, is not an should not pretend to be an art.