6. (A)
Question type: Identify the flaw
This argument concludes that people unconsciously fear the horse. The reasoning: Myths are often an expression of unconscious thoughts, and many cultures have a violent half-horse-half-human mythical figure, despite the fact that people generally consider horses to be gentle. The flaw in this argument, as (A) describes, is that even if the mythical figure reflects an unconscious fear, it does not necessarily reflect a fear of the horse half of the half-horse-half-human beast. Perhaps it is the human that we fear, or the animalistic tendencies of humans.
(B) is out of scope since the beast could or could not represent an unconscious fear of horses whether people have good reason to fear horses.
(C) is out of scope. There is no discussion of suppression.
(D) is out of scope. The conclusion does not depend on a culture spontaneously creating the myth instead of borrowing it from another culture. Either way, the beast could represent an unconscious fear (or not).
(E) is unsupported. While the argument does not explain why myths are used to express unconscious thoughts, it is stated as a premise and can be used to support the argument until it is proven false.