Which of the following compounds can cause the poisoning of drinking water?

Arsenic is introduced into water through the dissolution of rocks, minerals and ores, from industrial effluents, including mining wastes, and via atmospheric deposition. Arsenic related illness is usually caused by consumption of contaminated drinking water. Humans can develop resistance to certain arsenic concentrations. Shortly after absorption arsenic can be found in liver, spleen, lungs and digestive tract. Most arsenic is excreted, and residues may be found in skin, hair, nails, legs and teeth. Under conditions of prolonged exposure, many organs may be damaged, skin pigmentation may occur, hair may fall out and nail growth may stop.