LSAT Explanation PT 30, S4, Q4: A certain gene can be stimulated

LSAT Question Stem

If the statements above are true, it can be concluded on the basis of them that 

Logical Reasoning Question Type

This is a Must Be True question. 

Correct Answer

The correct answer to this question is A. 

LSAT Question Complete Explanation

Let's first analyze the passage and break it down into simpler terms. The passage tells us that chemicals in cigarette smoke can stimulate a specific gene, which in turn causes lung cells to metabolize those chemicals in a way that makes the cells cancerous. However, it also states that smokers who do not have this gene stimulated still have as high a risk of developing lung cancer as other smokers. To put it simply, even if this gene isn't stimulated, smokers still have a high risk of getting lung cancer.

Now, let's identify the question type and what it's asking us to do. This is a Must Be True (MBT) question, which means we need to find the answer choice that must be true based on the information provided in the passage.

Let's analyze each answer choice:

a) Stimulation of the gene by chemicals in cigarette smoke is not the only factor affecting the risk for smokers of developing lung cancer.

This answer choice is correct. The passage tells us that even if this gene isn't stimulated, smokers still have a high risk of getting lung cancer. This implies that there must be other factors contributing to the risk of developing lung cancer in smokers.

b) Nonsmokers have as high a risk of developing lung cancer as do smokers in whom the gene has not been stimulated.

This answer choice is not supported by the passage. The passage does not provide any information about the risk of lung cancer in nonsmokers.

c) Smokers in whom the gene has been stimulated are more likely to develop lung cancer than are other smokers.

This answer choice is incorrect because the passage states that smokers who do not have this gene stimulated still have as high a risk of developing lung cancer as other smokers. This means that the presence of the stimulated gene does not necessarily make them more likely to develop lung cancer.

d) The gene is more likely to be stimulated by chemicals in cigarette smoke than by other chemicals.

This answer choice is not supported by the passage. The passage only tells us that the gene can be stimulated by chemicals in cigarette smoke, but it does not compare this to the likelihood of stimulation by other chemicals.

e) Smokers are less likely to develop lung cancer if they do not have the gene.

This answer choice is incorrect because the passage states that smokers who do not have this gene stimulated still have as high a risk of developing lung cancer as other smokers. This means that not having the gene does not necessarily make them less likely to develop lung cancer.

Based on our analysis, the correct answer is A, as it must be true based on the information provided in the passage.