The detail that supports part A is the sentence that shows that without advertising, people would not have free access to television, magazines, newspapers, and internet content.
We can arrive at this answer because:
Your question is incomplete as you have not shown part A that this question is related to.
However, from questions similar to yours, we can see that part A shows that the theme of the text is that some people find advertisements annoying, but they are the ones that provide the public with necessary services and information.
More information:
https://brainly.com/question/15727939?referrer=searchResults