According to the text, what was the real master stroke that the researchers managed to accomplish ...

According to the text, what was the real master stroke that the researchers managed to
  accomplish in the study referred to as The Great American Values Test?

a. They were actually able to measure real values in their subject population.
  b. They were able to measure persuasion among viewers who had been interrupted
  during the program.
  c. They were able to get all the commercial channels in three different cities to
  broadcast the same program at the same time.
  d. They were able to persuade about 50 of the population to make a contribution to
  the environment.
  e. They were able to use a personal computer to analyze all of their data in less than
  24 hours.