PT63.S3.Q21 - Weed-killer data

akistotle

https://7sage.com/lsat_explanations/lsat-63-section-3-question-21/

I'm trying to understand this passage fully...

I thought the data on the effects of the weed-killer would be misleading when it was drawn from studies of the weed-killer under a variety of soil condition because the effectiveness fluctuates. That's why I chose (D). I thought the premise was telling us how soil conditions ruin the data.

After watching J.Y.'s video I now (sort of) get (D) actually weakens the argument, but can someone help me understand why my thought process (above) is wrong?

Also why is this not a necessary assumption question? I think the argument has jumped from one idea (the molecules of a certain weed killer) to another (the data on the effects).

GrecoRoman

It's the qualification in D that makes it weaken. "Variety of soil conditions [similar to those in which the weed killer is normally applied]. If D had said a "variety of soil conditions that the weed killer is not normally used in" then it would have been right. That is essentially what B says. So you were on the right track but just didn't realize the qualification actually made it weaken instead of strengthen. D probably sounded like what you were expecting so you may have subconsciously stopped reading the rest of the text after "variety of soil conditions" since you thought it was the right answer. I've done that countless number of times. Make sure to read fully and carefully to form those good habits. You got this.