Thanks for the question! So let’s recap the stimulus first. We know that the number of hospital ER visits by heroin users went up. The author then concludes that the use of heroin also went up.
So now we’re looking for an answer choice that’ll make the conclusion properly follow from the premise; in other words, this is a strengthen with sufficient premise. And the answer choice has to be airtight. In other words, it has to preclude all possibilities of the stimulus not being true. It has to make the conclusion 100% follow from the premise, without any possibilities or weird edge cases that would prove it wrong.
Now let’s take a look at (D) and see if it does that. It tells us that the methods of using heroin have changed since 1980, and the new methods are less hazardous. Sure, it’s possible that since heroin got safer, but visits have gone up, then there must be a lot more users. But that’s just that—a possibility. It’s not guaranteed, and so it can’t guarantee that the conclusion follows from the premises. It’s also possible that heroin use got safer, so fewer people used it, and people are coming in for other reasons (like better health insurance or more social acceptability). Since (D) doesn’t preclude these other possibilities, it can’t be the answer choice we need.
This question, just like all the questions assigned in the LSATMax course, now have detailed forward facing explanations that you can access when you “Review” your session. You will find unrivaled explanations written by our 99th-percentile instructors that include: (1) Argument or Facts, (2) Valid or Flawed, (3) Question Type, (4) Stimulus Summary, (5) Answer Anticipation, (6) Correct & Incorrect Answer Choice Explanations and (7) Key Takeaways. To ensure the optimal prep experience, please make sure you are taking advantage of these existing explanations before seeking further clarification on the message boards.
Hope this helps! Feel free to ask any other questions that you might have.
