In Minamata, Japan, people contracted mercury poisoning by

Eating contaminated fish

In Minamata, Japan, people contracted mercury poisoning by consuming fish and shellfish contaminated.

Explanation:

Minamata is a city located in Japan that is used as a fishing port. During 1965, what was known as "Minamata Disease" was developed which affected the fishermen of the city and their families.

It turns out that there were chemical factories that discharged wastes that contained an organo-mercury compound in the waters where the fishermen fished their fish. What caused the fish and shellfish to become contaminated, and when consumed by people caused them a mercury poisoning.

Suffering from mercury poisoning can cause Intellectual disability, paralysis, birth defects, blindness and even death.

This was the first disease listed as industrial pollution of seawater and managed to awaken movements for the protection of the environment.

In 1997 it was found that there was no longer any mercury in the waters of Minamata.

Therefore, the correct option is option B.