21) C

Percentage of men that have an abnormal PSA = 10% = 0.1
It is mentioned that of those with abnormal PSA, 26% will have cancer = 0.26
Men that will have cancer with abnormal PSA = 0.1 x 0.26 = 0.026 = 2.6%

Percentage of men that have normal PSA = 90% = 0.9
It is mentioned that of those with abnormal PSA, 26% will have cancer = 0.008
Men that will have cancer with normal PSA = 0.9 x 0.008 = 0.0072 = 0.72%

Total percentage = 2.6 + 0.72 = 3.32%
Hence the answer is C

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