Stimulus
While sales of other highly fuel-efficient automobiles are in decline, sales of the Hydro are rising. The Hydro's manufacturers attribute its success to the Hydro's price and very low fuel consumption. However, the Hydro is comparable in price and fuel efficiency to its competitors, so it is more likely people want to appear environmentally conscious to their neighbors.
What this question is testing
Your task
Find the assumption the argument requires in order for its conclusion to hold.
Common trap
Answers that would help the argument but aren't strictly required (sufficient, not necessary).
Winning move
Negate each choice — the right one breaks the argument when negated.
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