This is a tough one. I was agonizing over D vs. E as well.
What does the Question Stem tell us?
Explain (Discrepancy)
Break down the Stimulus:
Given that "yogurt ads tend to have more effect than milk ads in influencing consumer preference", how can we explain why "after LargeCo started advertising its milk and yogurt, sales of milk increased more"?
Any prephrase?
We normally don't try to prephrase answers to Paradox questions since the test loves to surprise us. We just echo the mantra of what we're trying to explain … "Why did milk sales increase more than yogurt sales?" (The one idea that sprung to my mind was maybe the store brand of yogurt was already popular, so there's not much room for sales growth).
Answer choice analysis:
A) Maybe. This sounds a bit like my prephrase, but lots of brands of yogurt are popular then it still would have been possible for yogurt ads to increase sales.
B) Okay, but maybe the same is true for yogurt. You go for yogurt, you usually don't get milk. This doesn't clarify why the ads are having more effect with milk.
C) Milk and yogurt are both dairy, so this doesn't draw a distinction. More importantly, this sounds like something that has always been true, not something that is an effect of the ads.
D) It sounds like if there's some OTHER factor that's lowering yogurt sales, then we can make sense of the fact that yogurt sales didn't go up as much as milk sales. I don't love this, because the yogurt ads could still take LargeCo's yogurt from super-low to low (and that might be a bigger increase in sales than that of milk).
E) This actually sounds like my hunch. (I stand by my earlier advice that it's not worth trying to guess the way in which they'll resolve the paradox). If customers were already buying LargeCo's yogurt, then the ads don't have much potential to improve sales. Meanwhile, consumers were buying milk based on cost, so perhaps the ads gave them a new direction for milk purchasing. There are a couple issues here though: 1. Is LargeCo's yogurt the cheapest or not the cheapest? It's outside knowledge, but the store brand of milk usuallly IS the cheapest brand of milk (ignoring sale prices). So according to (E), people would be already buying LargeCo's milk too. We're certainly not expected to use that outside knowledge, but in order for (E) to work, we have to assume that LargeCo's milk was NOT the cheapest milk. (E) only does its work if we think customers USED to buy the cheapest milk, and now after the ads, they buy the store brand. That's a dubious assumption to add. 2. The idea that store brand yogurt is already the default choice seems to go against the 1st half of the paradox (that yogurt ads are more effective than milk ads). How could yogurt ads be effective if people are tending to buy the store brand. (this would only align with the info we were given if we add the assumption that store brands of yogurt ADVERTISED their way into customers' "tendency to purchase them".
D vs. E is tough. I would start asking myself what assumptions I'm adding to each one to make them work.
For D, I have to assume that this yogurt-decrease affects LargeCo (but it does say "supermarkets throughout the nation").
And I have to assume that the yogurt-decrease is enough to make milk sales have a bigger increase than yogurt sales (but it does say "steep decrease").
For E, I have to assume that LargeCo's milk is NOT the cheapest at that store. (That's a tough one ... there's no support for that, and it kinda goes against our common sense)
I also have to assume that the tendency to buy store bought yogurt is so strong that there's not much room for sales growth, in order to explain why yogurt didn't improve as much as milk. (We have "tend to" = more than half the time, but if 55% of customers buy store brand, there's still plenty of headroom for sales growth).
Along the same lines, if I assume that store brands have little room for sales growth (that they're already claiming 90% or so of sales ), then I'm kinda invalidating the original idea that yogurt preferences are more easily shaped by advertisements.
So with those considerations, D seems like the safer answer (and it is the correct answer).
Takeaway/Pattern: Strong language is good on Explain questions (good on any question that begins "Which of the following, if true". Trap answers sometimes try to CHEAT the background constraint. We knew that yogurt ads are (more) effective at changing consumers' preferences, so can we really make sense of this info by then saying that consumers tend to purchase store brand yogurt?
#officialexplanation