【单选题】

Even those most______infections of all, those caused by viruses-formerly dismissed as untreatable because viruses disappeared into the inner labyrinths of the living cells, merging into the very genomes-are now becoming______to early treatments.
A．(A) refractory… amenable

B．(B) malignant … indifferent
C．(C) problematic… immune
D．(D) benign… resistant
E．(E) mysterious … inaccessible