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
When orthotoludine reagent is added to water and if free chohine is present, what colour will be produced? 
Select and explain. 
A. Pink, B. Yellow, C. Green, D. Red
B: Yellow
Answer: B: Yellow 
Explanation: None