After World War II, an earlier trend toward newspaper consolidation continued, and by 1970 newspaper accounted for the majority of newspaper circulation.

Chains, is the right answer.

Explanation:

Chain newspapers have been an important part of the pattern of daily journalism in the U.S at least since the close of the Second World War. Since 1923, approximately one-third of the newspapers in the U.S. have been chain circulation of all daily newspapers and two-fifth of the circulation of all Sunday newspapers in the U.S. have been chain newspapers. However, this data changed during the period of the Great Depression, for instance, during the Great Depression, One-third of the daily newspapers and two-fifth of all Sunday newspapers have been in Chain Newspapers.

i am sure the answer is d