This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Bacteriology, Subject name: Anatomy
A positive tuberculin test is indicated by an area of induration of 
Select and explain. 
A. <5mm in diameter, B. 6-9mm in diameter, C. >10mm in diameter, D. No induration
C: >10mm in diameter
Answer: C: >10mm in diameter 
Explanation: In this test 0.1 ml of PPD containing 5 TU is injected intradermally on the flexor aspect of the forearm with a tuberculin syringe, raising a wheal. The site is examined48-72 hrs later and the induration of: > 10mm: positive 6-9mm : equivocal /doubtful <5mm : negative Ref: Textbook of microbiology; Ananthanarayan and paniker's; 10th edition; Pg: 360