Versos! Aristotle said that Logos is like logic, Pathos is appealing to people through emotion, and Ethos is how credible somebody is, like how you would believe a doctor more than you would a ten year old. Versos is not one :)
The most credible source in terms of researching the effects of smoking is letter b, research article in a scientific journal. It is because a credible source means that it is valid or could be relied on in which the research article is, because it has been researched and holds validity of which contains proof. Other choices does not correspond to the question for they don't hold any validity or proof in the topic that could be reliable.
Answer:
he is different from others
Explanation:
