Q13)Strengthen Questions

Toxicologist: A survey of oil-refinery workers who work with MBTE, an ingredient currently used in some smog-reducing gasoline, found an alarming incidence of complaints about headaches, fatigue, and shortness of breath. Since gasoline containing MBTE will soon be widely used, we can expect an increased incidence of headaches, fatigue, and shortness of breath.

Each of the following, if true, strengthens the toxicologist’s argument EXCEPT:

(A) Most oil-refinery workers who do not work with MBTE do not have serious health problems involving headaches, fatigue, and shortness of breath.
(B) Headaches, fatigue, and shortness of breath are among the symptoms of several medical conditions that are potentially serious threats to public health.
(C) Since the time when gasoline containing MBTE was first introduced in a few metropolitan areas, those areas reported an increase in the number of complaints about headaches, fatigue, and shortness of breath.
(D) Regions in which only gasoline containing MBTE is used have a much greater incidence of headaches, fatigue, and shortness of breath than do similar regions in which only MBTE-free gasoline is used.
(E) The oil-refinery workers surveyed were carefully selected to be representative of the broader population in their medical histories prior to exposure to MBTE, as well as in other relevant respects

It's a weaken question rather than strengthen i will pick option B too though the wordings are not quite precise as expected.

Toxicologist's argument
MBTE -----> increased incidence of headaches, fatigue and shortness of breath

what can weaken this

- if the cause of headaches, fatigue and shortness of breath is attributed to something else other than MBTE

what's the OA

B it is.

Since it is a Strengthen-X question. We should find a point which do not strengthen the stimuli.

B is the best possible answer
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To reach a port, we must sail—Sail, not tie at anchor—Sail, not drift.

E provides the necessary condition for the survey`s conclusion.
Without this condition you could have some doubts regarding the group of people.

If you read book CRITICAL REASONING BIBLE, you will see that the best part of the book is about causal relation and if you read this part, you see this question is too easy.