Of the five bill collectors at Apex Collection Agency, Mr. Young has the highest rate of unsuccessful collections. Yet Mr. Young is the best bill collector on the agency’s staff. Which one of the following, if true, most helps to resolve the apparent discrepancy ？（）
A．Mr. Young is assigned the majority of the most difficult cases at the agency.
B．The other four bill collectors at the agency all consider Mr. Young to be a very capable bill collector.
C．Mr. Young’s rate of collections per year has remained fairly steady in the last few years.
D．Before joining the agency, Mr. Young was affiliated with the credit department of a large department store.
E．None of the bill collectors at the agency has been on the agency’s staff longer than Mr. Young has.
