If you do not have any experience in an area, what is one other way to establish credibility in a persuasive essay? In a short paragraph

Choose the sentence that is not logically connected in the paragraph. (1) one final effect of radio and tv on the language must must be noted. (2) there is no doubt that these great media of information have cut down considerably the time that used to be devoted to reading. (3) radio and tv may enhance the spoken word. (4) they tend to lower comprehension levels.