Confused

We are told that some cleaning fluids release toxins, such as formaldehyde and benzene. The stimulus tells us that these toxins do not pose any danger in well-ventilated houses; however, they do in well-insulated houses because the toxins get trapped. The passage then cites to recent tests that show that houseplants remove some toxins from the air and, in doing so, eliminate the danger posed by toxins getting trapped in poorly ventilated homes. The stimulus then refers to a specific test where 20 large plants successfully eliminated formaldehyde, one of the toxins released by cleaning fluids, from a small, well-insulated house. So, we can see that having plants can help minimize the risk of using cleaning fluids in a poorly ventilated home, because the plants remove some of the toxins released by the cleaning fluids. Thus, we are lead to conclude that houseplants can help resolve the issue posed by cleaning fluids releasing toxins, which getting trapped in well-insulated (poorly ventilated) houses, i.e. answer choice (D): "Keeping houseplants can compensate for some of the negative effects of poor ventilation." Hope that clears things up! Please let us know if you have any more questions.

Why should we assume well-insulated to mean poorly-ventilated? There is no premise to suggest that a home cannot be both well-insulated and well-ventilated. Just curious. Thanks.

Take note of the second sentence: "This is not a problem in well-ventilated houses, but it is a problem in houses that are so well insulated that they trap toxins as well as heat." So we are inferring from this that such a well-insulated house is not well-ventilated, because if it were well-ventilated then the cleaning products releasing toxins into the household air supply would not be an issue. Hope that clears things up! Please let us know if you have any more questions.

I originally chose E. Is this answer incorrect because it only refers to "houseplants" without saying how many, so we cannot conclude that well insulated house with houseplants will have fewer toxins than a well ventilated house without them? I guess this question also does not say whether the respective houses contain or use synthetic products. I hope I'm on the right track here!

I originally chose E. Is this answer incorrect because it only refers to "houseplants" without saying how many, so we cannot conclude that well insulated house with houseplants will have fewer toxins than a well ventilated house without them? I guess this question also does not say whether the respective houses contain or use synthetic products. I hope I'm on the right track here!

Yes exactly. We never discuss amount so we cannot make such a conclusion. Nice reasoning skills!