PART A: The author's main purpose in the final section "Why is the News Sometimes Controversial" is to encourage readers to not accept the information that news outlets provide them and seek answers on their own.
PART B: The detail from the text that best supports the answer to Part A is: "It is impossible to avoid bias completely, but news writers and news readers can still do a lot to make sure the information they share and read is accurate." (Paragraph 10)