【单选题】

It may be ------- to obtain soap that is not antibacterial, given its ------- as a household cleansing product, but according to a new study, such products may be a waste of time.
A．(A) difficult... ubiquity

B．(B) imprudent... weakness
C．(C) traditional ... relevance
D．(D) revolutionary ... innovation
E．(E) extravagant... expense