The Waterbucks chain of hospitals decided to start a health magazine about different diseases and their respective cures

Since the team wasn't sure if the magazine was something the public could easily understand, they selected random people and gave them each a draft of the magazine. Each person was asked to read the entire publication, and then comment on whether or not it was easy to understand. What technique did the team apply, and how did it help?
a) Copy testing; to understand the education level of the audience
b) Content analysis; to measure the amount and nature of media coverage
c) Omnibus survey; to give the NGO exposure to the thoughts about their messages
C
d) Focus group; to identify the range of attitudes of the audience

a