### The solution gives detailed discussion on definitions and calculations of specificity and sensitivity. Some further topics such as positive predictive value, negative predictive value, Lead time bias and length-bias are also explained. All formula of specificity and sensitivity are shown and explained with specific examples.

1) Sensitivity is: A. The probability that a test correctly classifies as positive those who have preclinical disease. B. The probability that a test correctly classifies individuals without preclinical disease as negative C. The probability that those who test positive have the preclinical disease D. The probability that t