【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