How was agenda setting defined in the lectures?单项选择题

a. The media have the ability to tell us what to think, and they have the ability to tell us what to think about.

b. The media don't have the ability to tell us what to think. But they do have the ability to tell us what to think about. ​

c. The media have the ability to tell us what to think, but we are also slowly gaining control of this process through social media.

d. The media have the ability to tell us what to think about, and Agenda Setting refers to our capacity to resist and challenge this power.