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: Social & Preventive Medicine
Tuberculin unit is 
Select and explain. 
A. 1 unit of PPD RT3, B. 0.0001 mg, C. 0.1 mg BCG, D. None of the above
A: 1 unit of PPD RT3
Answer: A: 1 unit of PPD RT3 
Explanation: None