Which metal causes Minamata disease?
A. Copper
B. Lead
C. Manganese
D. Mercury

Hint: In Japan there is a company named chisso and produces methylmercury that spreads in the aquatic water. With the increase of the water environment the two types of effect produce Bioaccumulation and Biomagnification that are also part of the "Minamata disease".

Complete answer:
Minimata is a disease found for the first time in Japan sometime known as “chisso minamata”. It produces a neurological disorder that is generated by the methylmercury. And people who eat seafood suffer from excess methylmercury that causes minamata disease. It was discovered in 1956 in Japan and the symptoms of these disease ataxia, numbness in the hands and feet, general muscle weakness and the severe adverse event of this disease is a cause of death.
The several elements of Mercury (Hg) are highly toxic when it is inhaled by the person directly and also cause damage to the internal organs like kidney, liver because the toxic molecules like carboxylic, amide and amino acids.
The treatment of minamata disease to stop eating sea foods in which Mercury exists and keep away the affected person for a few times. The bacteria is segmented in the methylmercury and people use water for drinking and eat seafood highly affected by the minamata disease. And contaminated fishes (shellfish) transfer to the human body. But this disease is also found in small quantities in the Japanese people.

Therefore the correct answer is option (D). Mercury.

Note: It is a neurological disease that can cause poisoning methylmercury. It is also an environmental disease and Japanese are most effective with that disease.