Itai-Itai disease is caused by chronic poisoning of

Mercury
Nickel
Cadmium
Lead

The correct answer is (c). Itai-Itai disease is a bone disease caused by chronic cadmium poisoning. It is characterized by severe bone pain, fractures, and kidney dysfunction. The disease was first identified in Japan in the 1950s, and it is thought to have been caused by the contamination of drinking water with cadmium from industrial waste.

Mercury is a heavy metal that can cause a variety of health problems, including neurological damage, kidney damage, and reproductive problems. However, it is not known to cause Itai-Itai disease.

Nickel is a metal that is used in a variety of products, including stainless steel, batteries, and coins. It can cause allergic reactions in some people, but it is not known to cause Itai-Itai disease.

Lead is a heavy metal that can cause a variety of health problems, including neurological damage, kidney damage, and reproductive problems. However, it is not known to cause Itai-Itai disease.

Cadmium is a heavy metal that is used in a variety of products, including batteries, pigments, and stabilizers. It can cause a variety of health problems, including bone disease, kidney disease, and cancer. Itai-Itai disease is caused by chronic cadmium poisoning.