A person with a type B lipid profile is at much greater risk of heart disease than a person with a type A lipid profi...

Naz on June 22, 2015

We are told that people with type B lipid profile are at much greater risk of heart disease than those with type A lipid profile.

After the experiment we know that the type A lipid profile volunteers showed no benefit from the diet, and 40% of them shifted to type B profiles.

Well, we know that type B lipid profiles are at much greater risk of heart disease than type A lipid profiles. So, the 40% of type A profile volunteers that switched to B profiles actually raised their risk of heart disease after the experiment, i.e. after having been put on the low-fat diet.

Thus, answer choice (E) must be true according to the information in the passage: "For at least some of the volunteers in the experiment, the risk of heart disease increased after having been put on the low-fat diet."

Hope that clears things up! Please let us know if you have any other questions.

Julie-V on July 29, 2019

how can we eliminate (C)? Is it not the best answer because it wouldn't be the best fit for a must be true (and maybe sounds like a better choice for a strengthen question?) ?

Victoria on August 9, 2019

Hi @Julie-V,

You are right. Answer choice C does not have to be true, but it could help to strengthen the argument as it would mean that the changes experienced by the volunteers would be more likely to be a result of the switch to a low-fat diet.

Answer choice E is a much stronger choice for a must be true question. We know that "a person with a type B lipid profile is at much greater risk of heart disease than a person with a type A lipid profile" and that some type A volunteers shifted to type B profiles after adopting the low-fat diet. This means that these type A - > type B volunteers would have experienced an increase in the risk of heart disease after being put on the low-fat diet making E the correct answer.

Hope this helps! Please let us know if you have any further questions.