A recent study found that people who drink coffee daily have a lower

Question

A recent study found that people who drink coffee daily have a lower risk of developing Alzheimer's disease. The study surveyed 1000 people over the age of 60, of whom 500 drank coffee daily and 500 did not. Of the 500 coffee drinkers, only 50 developed Alzheimer's disease, while 100 out of the 500 non-coffee drinkers developed the disease. Therefore, drinking coffee daily reduces the risk of Alzheimer's disease.

Which of the following statements, if true, would weaken the argument above?

A) The study did not take into account the participants' family history of Alzheimer's disease.
B) The study did not take into account other lifestyle factors that may affect the development of Alzheimer's disease.
C) There is evidence that coffee can increase blood pressure in some people.
D) The participants in the study who drank coffee daily also tended to exercise more and eat a healthier diet.
E) The study only surveyed participants in one geographical region and may not be representative of the wider population.

LakshitaGupta · Answer

Can someone help me with why 'b' is not the right answer

Gautam0525 · Answer

Hi, 
B is not correct because it considers lifestyle factors, about which we know nothing of. That's an outside knowledge or out of scope choice. Whereas, D says not only coffee but also Diet and Excercise contributes to this. Hence, that weakens the conclusion that Coffee drinkers reduces the risks of this disease.

Hope this helps!

avigoesforMBA · Answer

Hey!

One of the core features of GMAT options is that the answer is the best answer out of the options available.

B) says that there  MIGHT BE  some other factors which lead to the result

D) points out those other factors -  exercising and healthy eating  that result in the conclusion.

Think of it as: Lakshita scored 745, because she used to consume coffee.

B) - There might be some other factors
D) - Lakshita used to consume coffee since she often studies for long

It would make sense to select D right?

saksh4M · Answer

hi,

my question is dosent D assume that extra exercise and diet are related to the disease. while option B weakens by saying the study itself is flawed and we dont need to assume anything

avigoesforMBA · Answer

The question doesnt assume. It asserts.

“Which of the following, if true” is what the questions reads.

So you dont need to assume anything, anywhere. You just need to consider these true because the question says so.

Now, when that’s clear - D states the factors which prove that coffee is not related. B guesses (by using the word “might”) that there might be something else and not coffee.

svsivakrishna · Answer

Hi,

As per conclusion:

Cause: Drinking coffee

Effect: Less chance of alzhemeirs disease

Option B states that other lifestyle factors  "May affect" . we dont know how it affects and whether positively or negatively.

Option D explicitly states that people who drank coffee also exercised and ate healthy diet.

This is the case of  alternate cause  where coffect might not be the reason for less chance of alzhemeirs disease and instead healthy diet and exercise may have caused it.

CareerLauncherMBA · Answer

Argument Summary:

Premise: In a study of 1,000 people aged 60+, 50 out of 500  coffee drinkers  developed Alzheimer’s, while 100 out of 500  non-coffee drinkers  did.   
   Conclusion: Therefore,  drinking coffee daily reduces the risk of Alzheimer's disease .
    
  So the conclusion is based on a  correlation  observed in the study. To weaken the conclusion, we need to show that the lower rate of Alzheimer’s among coffee drinkers might be due to  something else , not coffee itself.  
 
   What Would Weaken the Argument?   
  A  good weakening statement  should:  
 
   Show that the difference might be due to  another variable  (confounding factor),   
   Or indicate a  flaw in the study's design or representativeness .
    
  Let’s evaluate each choice:  
       
    A) The study did not take into account the participants' family history of Alzheimer's disease.    
 
    Effect : Family history is a known risk factor.   
   If more non-coffee drinkers had a family history of Alzheimer’s,  that  could explain their higher incidence, not lack of coffee.   
    This weakens  the argument — but is it the strongest?
    
   Keep for now  — it's a decent weakener.  
       
    B) The study did not take into account other lifestyle factors that may affect the development of Alzheimer's disease.    
 
    Effect : Lifestyle factors like diet, exercise, sleep, etc., can affect Alzheimer’s risk.   
   If coffee drinkers also lived healthier lives overall,  those factors  (not coffee) could explain the lower risk.
    
   This is a strong weakener  — it introduces  multiple potential confounding variables , not just one like in A.  
   Keep – stronger than A.   
       
    C) There is evidence that coffee can increase blood pressure in some people.    
 
   This is  irrelevant  to Alzheimer’s.   
   Even if coffee increases blood pressure, that  doesn’t address  whether it lowers Alzheimer’s risk.   
    Does NOT weaken  the argument.

D) The participants in the study who drank coffee daily also tended to exercise more and eat a healthier diet.    
 
   This is a  specific version of B : it directly says that coffee drinkers had other healthy habits.   
   This gives  a clear alternative explanation : maybe it’s the healthier lifestyle — not the coffee — that led to lower Alzheimer’s risk.
    
   Best weakener  — directly points to a  confounding variable .  
   Strongest option.   
       
    E) The study only surveyed participants in one geographical region and may not be representative of the wider population.    
 
   This  challenges generalizability , not the  logic  of the conclusion.   
   It means the study might not apply to everyone, but it  doesn’t undermine the cause-effect link  the conclusion tries to establish.   
    Only weakens external validity, not the core argument .

Final Evaluation:   
      Option    
    Effect    
    Keep/Eliminate    
 
    A   
   Suggests possible confounding variable (family history)   
   Keep   
 
    B   
   Suggests multiple confounding variables   
   Keep   
 
    C   
   Irrelevant health detail   
    Eliminate    
 
    D   
   Specific confounding variables (healthier lifestyle)   
    BEST    
 
    E   
   About generalizability, not causal logic   
    Eliminate

Correct Answer: D  
  D) The participants in the study who drank coffee daily also tended to exercise more and eat a healthier diet.
  
 This clearly  undermines the causal link  between coffee and Alzheimer’s reduction by pointing to  other correlated behaviors  that could be responsible.

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Sajjad1994 · Answer

Official Explanation

Step 1: Understand the Argument

Premise:    A study of 1,000 people over 60 found that:

- 50 out of 500 coffee drinkers developed Alzheimer’s. 
 - 100 out of 500 non-coffee drinkers developed Alzheimer’s.

Conclusion: Drinking coffee daily reduces the risk of Alzheimer’s disease.

Step 2: Identify the Question Type

This is a  "Weaken the Argument"  question. We need to find a statement that undermines the causal claim that coffee reduces Alzheimer’s risk.

Step 3: Look for Potential Weaknesses in the Argument

The argument assumes that coffee is the  only  factor affecting Alzheimer’s risk. However, other variables (e.g., genetics, diet, exercise) could explain the difference. A good weakener will introduce an  alternative explanation  or  confounding factor .

Step 4: Evaluate the Answer Choices

A)    This suggests genetics could be a confounding factor. However, it doesn’t directly explain why coffee drinkers had lower rates. Weak weakener.

B)    This is broad and hints at confounding variables, but it doesn’t specify which factors.

C)    Irrelevant. The argument is about Alzheimer’s, not blood pressure.

D)   Strong weakener!    This provides an alternative explanation: healthier habits (not coffee) may have caused the lower Alzheimer’s risk.

E)    This critiques generalizability, but it doesn’t directly challenge the causal link.

Answer: D

ahddhah · Answer

I would avoid this question since its playing on very fine choice of words because there is genuinely no difference in B and D. One can say B sounds more like a logical flow but not weakner. I agree to that but that is not what we shall test in question.

Advait01 · Answer

In B we dont know which lifestyle choices are taken, it may worsen or reduce the risk of the disease
Now since we dont know definitively, we go with D

A recent study found that people who drink coffee daily have a lower

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Option	Effect	Keep/Eliminate
A	Suggests possible confounding variable (family history)	Keep
B	Suggests multiple confounding variables	Keep
C	Irrelevant health detail	[color=#ee0000]Eliminate[/color]
D	Specific confounding variables (healthier lifestyle)	[color=#00b050]BEST[/color]
E	About generalizability, not causal logic	[color=#ee0000]Eliminate[/color]

GMAT Critical Reasoning (CR) Questions

A recent study found that people who drink coffee daily have a lower

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