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
Wha is HTH? 
Select and explain. 
A. Hormonal contraceptive, B. Water disinfectant, C. Insecticide, D. Rodenticide
B: Water disinfectant
Answer: B: Water disinfectant 
Explanation: High test Hypochlorite (HTH) or perchloron is a calcium compound which contains 60 to 70 % available chlorine for disinfection. Ref: Park 21st edition, page 661.