One reason early twentieth century muckrakers were able to have a significant impact on society was because

a. sales and circulation of newspapers and magazines increased.

Explanation:

According to a different source, these are the options that come with this question:

a. sales and circulation of newspaper and magazines increased.

b. most citizens of the US were already convinced that Jim Crow laws must be overturned.

c. drought conditions in the Midwest drew attention to social problems.

d. they had the sympathy and support of industrialist like Andrew Carnegie and John Rockefeller.

Muckrackers was the name given to a group of journalists during the early twentieth century. These journalists were dedicated to exposing the injustices they noticed in society. Some of the subjects that muckrackers wrote about were the corruption of the government, the terrible conditions of the poor, the cruelty of Jim Crow laws and the horrible working conditions of factories.