Cultural trends tend to be an important determinant of the prices of materials
Why this is right
This is definitely something we pick while reassuring ourselves, "Remember, it doesn't have to be perfect; just best available." This does what we expected --- it reinforces the fact that "being / not being fashionable" has a causal impact on price. Where it sucks is that it speaks more broadly of cultural trends (fashion is one example of that), and it says tend to. "tend to" was too strong in (C) and it's also too strong here, but (C) had some negative support. This is better than (A) because we only know that fashion is a factor, not that it is more important than the materials being made. (D) had counterevidence because we know that how fashionable something is also affects price (it can't just be appearance). (B) brought up practical which has zero support. So the way we come home to a dud like this is thinking (A) too broad a category / too strong a statement of causal impact (B) totally unmentioned concept (C) too strong + counterevidence (D) too strong + counterevidence (E) no counterevidence / no totally out of scope concepts / safer strength of language when it comes to stating causal impact But, yeah, tough correct answer to go along with. We have to remind ourselves that we have some support for this (and no counter-support for this) in order to ultimately decide that this is the answer we have the most support for, given the available options.
Skill tested: Most Supported · how this choice captures the argument's function is the move to repeat next time.