What is the author's attitude towards doctors

A．the path of toxic gases from a nuclear power plant explosion
B．where incoming nuclear missiles might strike
C．the average annual rainfall for North Dakota
D．the amount of pollution in the air

A．has to be eliminated before correct readings can be obtained
B．would be impossible to convert to data that a computer would accept
C．might lead to new applications and improve effectiveness of present uses
D．would make ray tracing obsolete