This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Microbiology
Negative Mantoux test is when induration is 
Select and explain. 
A. <10 mm, B. <15 mm, C. <20 mm, D. <5 mm
D: <5 mm
Answer: D: <5 mm 
Explanation: None