一題傷腦筋的邏輯

Blood banks will shortly start to screen all donors for NANB hepatitis. Although the new screening tests are estimated to disqualify up to 5 % of all prospective blood donors, they will still miss tow-thirds of donors carrying NANB hepatitis. Therefore, about 10 % of actual donors will supply NANB-contaminated blood.
A. Donors carrying NANB hepatitis do not, in a large percentage of cased, carry other infections for which reliable screening tests are routinely performed.
B. Donors carrying NANB hepatitis do not, in a large percentage of cases, develop the disease themselves at any point.
C. The estimate of the number of donors who would be disqualified by tests for NANB hepatitis is an underestimate.
D. The incidence of NANB hepatitis is lower among the potential blood donors than it is in the population at large.
E. The donors who will still supply NANB-contaminated blood will donate blood at the average frequency for all donors.
答案是A.
基本上，题目我看不太懂，更不用说里面的因果逻辑了，有高人可以把题目翻成中文吗，tks.[em12]