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
What is the amount of bleaching powder required to disinfect 455 litre of water if 4, 5, 6 cup shows distinct colouration in Horrock’s apparantus? 
Select and explain. 
A. 2 g, B. 8 g, C. 6 g, D. 4 g
B: 8 g
Answer: B: 8 g 
Explanation: None