Concept:The media express their own opinion on national matters through editorial commentary.Explanation:Editorial commentary is the part of newspapers, magazines, and broadcast media where the media house presents its views on public issues.It is through this channel that electronic and print media make their voices heard on national issues.Public notices and advertisements are paid or official announcements, not expressions of media opinion.A documentary is usually factual or informational, not an opinion piece.Answer:D. editorial commentary