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: Dental
In gingival bleeding index given by Ainamo and Bay, positive score is taken at what time after appearance of bleeding on probing? 
Select and explain. 
A. 10 Sec., B. 20 Sec., C. 30 Sec., D. 40 Sec
A: 10 Sec.
Answer: A: 10 Sec. 
Explanation: None