Answer:
wind blew the rocks over the edge of the hillside
I HOPE THE ABOVE INFORMATION WILL HELP YOU A LOT.
The correct answer is B. Trust, competence and ethos.
The speaker will inspire credibility from the audience when it perceives his or her character and their ethos concerning the topic they are presenting. If they know it really well, they will speak with authority, which will engender trust. Their competence is manifested and it's easier for the audience believe and received what it's being conveyed.
An isolationist country would likely have state-run media in order to control the information that the populous is allowed to see and not see, as well as having it to use as a vehicle for propaganda. This phenomenon is observable today in North Korean media, for example.