How did scientists change society's view of smoking after 1960?

a. they showed that it relieved stress.
b. they showed that smoking causes cancer.
c. they showed that cigarettes could be made more cheaply.
d. they showed that smoking increases stress.

After some tedious experiments in the late 20th century, scientists have shown evidence that the chemicals and materials found in the cigarette can cause diseases in the long term. In the 1940s and later years, there were increased cases of lung diseases and lung cancer, where it was supposedly a very rare disease.

They changed society's view of smoking after 1960 by showing that smoking causes cancer.

B. They showed that smoking causes cancer.

There was a noted change in the society's view on smoking after 1960. Such change was influenced by declaring tobacco as an addiction and that it can cause cancer. It started in the 1964. 

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