Sale Analyst: When polled, all consumers consistently say that, for ho

Sale Analyst: When polled, all consumers consistently say that, for household staples, they would buy the lowest cost items. Even when other factors, such as inherent product quality, are introduced, all consumers still argue that low cost should be the highest priority in buying household staples. Therefore, these responses demonstrate how little most people are aware of the actual priorities that drive their purchasing decisions.

Conclusion - people don't know about actual priorities that drive purchasing decisions.
Note - As per author , correct priorities should not be limited to cost. We need to consider "Product Quality" as well -

The conclusion above is properly drawn if which of the following is assumed?

(A) Many people on restricted incomes are not able to afford any brands of household staples more expensive than the lowest cost items.
-- Passage is not about affordability. It is about awareness.

(B) Consumers do not always have the motivation to be truthful about their real motivations when responding to a stranger giving a poll.
-- Need not be always true. ya but if tree it strengthens the conclusion , so it is a strengthener.

(C) Often, higher priced brands of household staples, especially organic versions, are more nutritious and are rated better-tasting in double-blind tests.
-- Doesn't even support the conclusion.

(D) People often give unreliable and self-contradictory explanations after the impulse purchase of a snack or dessert.
-- irrelevant

(E) For many household staples, famous name brands with recognizable ads consistently outsell less expensive brands of the same products.
-- correct answer. Provides the reality with evidence.(Famous name brands outsell less expensive brand). So price is not the only criteria.