A new screening test has a sensitivity of 90% and a specificity of 70% in a group of 200 young Russian prisoners in which the prevalence of tuberculosis is 50%. The number of TN tests in this sample is: TUBERCULOSIS NO TUBERCULOSIS TOTAL TEST POSITIVE TP FP TEST NEGATIVE FN TN TOTAL 200 A. 100 B. 90 C. 70 D. 30