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
To find out whether the water has been properly chlorinated, the test used is - 
Select and explain. 
A. Horrock's test, B. Oho-toludine test, C. Presumptive col i form test, D. Total bacterial count
B: Oho-toludine test
Answer: B: Oho-toludine test 
Explanation: Ans. is 'b' i.e., Oh o-toludine test