@hallerae the conclusion here is, "The most rational public health strategy, therefore, would place much more emphasis than at present on fully informing people about the transmission of diseases caused by microorganisms, with a view to minimizing the incidence of such diseases."
So let's put (C) in context:
"There is good reason to make a particular change to public health policy."
The change (C) is referring to is placing "much more emphasis than at present on fully informing people about the transmission of diseases caused by microorganisms" as opposed to assuming that application of biochemical research will achieve a complete victory over microorganisms.
Hope that helps! Please let us know if you have any other questions.
