The key point was that Kennedy challenged Nixon to a series of televised debates. It was the first televised presidential debate in American history.
In 1960, 88 % of American homes had television. About 2/3 of the electorate watched the first debate on TV. Nixon was recovering from a knee injury, he looked drained. Kennedy, meanwhile, had been resting in a hotel for an entire weekend, he looked tan and confident.
Most Americans watching the debates voted for Kennedy, most radio listeners seemed to give the edge to Nixon.
What exactly is the question
B - agenda
An agenda is what the author really wants to point out (their underlying message) and it's typically written in a way where it's somewhat hidden. Example: political ads - they have an agenda for what they want to talk about and why it's important.