The argument tells us that technology discourages critical thinking. And critical thinking is the only protection against demagogues. This is an EXCEPT question, meaning all of the answer choices could be true EXCEPT for the correct one.
(D) argues that that mere presence of an orderly system is an adequate protection against demagogues, which directly contradicts the argument - "critical thinking is the ONLY adequate protection..". We cannot ascertain the truth or falsity of any of the remaining answer choices, leaving open the possibility that they could be true.
(A) No political demagogues in tech societies
This could be true because technology only discourages critical thinking, we cannot infer that there is no critical thinking in a technological society
(B) Political demagogues are not the only ones who exploit emotions
This could be true, nothing in the argument says demagogues are the only ones who do that.
(C) Highly emotional people are more easily exploited
This could be true, argument suggests that exploitation is achieved via emotionally-loaded language.
(E) The mere presence of electronic communication provides protection against erosion of media freedoms.
This could be true and out of scope of the argument, the argument only concerns demagogues not erosion of media freedom.