the primary means of mass communication changed from what to what in the mid - twentieth century?\nfrom…

Brief Explanations:

In the mid - twentieth century, radio was a dominant mass - communication medium earlier, and then television emerged and became more prevalent as a primary means of mass communication. The internet became a major mass - communication tool later in the century, telegraph was earlier than the mid - twentieth century as a major medium, and telephone is not a primary mass - communication medium like radio or television.

Answer:

D. From radio to television