Commenting on this thread for anyone else who might be in the comments searching for clarity - another important element here requires the inference that the reason creosote deposits are dangerous in the first place is because they're flammable and may ignite inside the chimney. AC C not only mentions that open flames are more dangerous in a particular scenario, its the scenario that is directly relevant to the main piece of evidence in the argument. Creosote deposits may be dangerous inside, but now we know there are bigger dangers of open flames that are directly relevant to the claim made in the stimulus. If a new concept - in this case, igniting inside the chimney - is brought up in the conclusion and not the premises, you should flag it immediately for potential relevance in strengthen/weaken questions!

Hi! I bought this book but can't decide whether to start from the beginning or just use it as needed. I'm not sure I have enough time to devote to the book to complete every page, in your experience are sections in isolation still useful or do you recommend reading the entire book through? Thanks in advance!

The conclusion of the argument is that incentives to plant trees are hastening (speeding up) global warming. Why? Because native grasses absorb and store carbon dioxide more effectively than do trees.

This logic requires that D be correct. Take the negation: It is not true that some of the trees planted in response to the incentives are planted where native grasses would otherwise be growing.

If the logic of the argument is that, because native grasses are a better option than trees for preventing climate change (even though trees are still positive), planting trees makes climate change worse, then it is required that it is assumed these trees would be planted INSTEAD of native grasses. And if you negate answer choice D, this is not true, blowing up the argument.

I hope that helps! I think negating is the easiest way to approach these qs, especially If you don't have a general feel for what the right answer will be after reading the stim.