Critical Reasoning

The recent construction of the chemical plant on the shores of Lake Blue has introduced a new pollutant into the water: toxidil. Toxidil first works its way into the ecosystem through the underwater plant life. These plants absorb the pollutant, which is then transmitted to the local fish population when the vegetation is ingested. Fish so tainted appear healthy, but their meat, when consumed by humans, leads to serious health problems. The population living in the vicinity of Lake Blue will undoubtedly suffer a decline in health due to the new chemical plant.

Which of the following is an assumption necessary for the author's conclusion?

(A) Other pollutants are not also detrimental to human health.

(B) The fish in Lake Blue are consumed by the people who reside nearby.

(C) The first reported incidences of fish tainted with toxidil occurred in Lake Blue, and not elsewhere within Canada or the United States.

(D) Currently, the only source of toxidil in the world is the chemical plant at Lake Blue.

(E) Banning chemical processes that produce toxidil will merely cause the owners of the chemical plant to continue these same processes in secret at Lake Blue.

What's wrong with options C and D?

OA B