【单选题】

It can be inferred that which of the following situations is likely to be most problematic to an adherent of the "essentialist" method of pathological taxonomy
A．(A) A patient suffering from fever, in which the virus that is apparently responsible for the symptoms has not been isolated

B．(B) A patient suffering from lung inflammation which, though resembling other inflammations, does not respond to any known treatments
C．(C) A patient suffering from a genetic anomaly whose cause may be known but whose consequences remain unidentified
D．(D) A patient infected with a variety of bacteria that is known to cause two diseases with dissimilar symptoms
E．(E) A case of a patient with symptoms that may have arisen from two known diseases of different sources