This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Water, Subject name: Social & Preventive Medicine
Most undesirable metal in drinking water is: 
Select and explain. 
A. Iron, B. Copper, C. Zinc, D. Lead
D: Lead
Answer: D: Lead 
Explanation: Undesirable metal in drinking water: iron, manganese, zinc, copper, aluminum, lead MOST undesirable metal in drinking water: Lead. Lead was earlier seen in drinking water when water was being supplied through lead pipes. Undesirable salts in drinking water: chloride, fluorides, nitrites, nitrates, calcium, magnesium. Undesirable gases in drinking water: ammonia, hydrogen sulphide, methane.