Minamata disease is caused by pollution of water by:-
A. Cadmium
B. Mercury
C. Lead
D. Arsenic.

Hint: Minamata disease is a methylmercury poisoning with neurological symptoms and caused by the daily consumption of large quantities of fish and shellfish that were heavily contaminated with the toxic chemical are produced in factories and are thrown into the sea.
Once nerve cells die, they cannot regenerate. It is difficult to cure patients with severe nerve cell damages. Residual symptoms are treated with medication or rehabilitation. These symptoms can be controlled to much extent. This disease is usually found in Japan.

Complete answer:
CADMIUM:- Itai-itai (ouch-ouch) disease, a bone disease caused by cadmium poisoning, is one of the most serious health problems caused by industrial pollution in Japan. Hence this option is incorrect.
MERCURY:- Minamata disease is caused due to methylmercury poisoning of Minamata bay of japan. So , this option is correct.
LEAD:- Occupational exposure to lead increases the risk of cardiovascular disease, in particular: stroke, and high blood pressure. Thereby , this option is wrong.
ARSENIC:- Arsenic is a known human carcinogen associated with skin, lung, bladder, kidney, and liver cancer. So , this option is incorrect.

Our correct option is d, that is mercury.

Note:
Minamata bay is heavily polluted due to waste generated from the factories and then discharged into this bay. This caused Minamata disease as it occurred from Minamata bay.
Many people were killed due to this disease about 9,000.
Many people suffered from mercury poisoning. The waste contains mercury in it. It occurred in Japan.