Researcher: Hard Water Contains More Calcium And Magnesium GMAT Critical Reasoning

Question: Researcher: Hard water contains more calcium and magnesium than soft water contains. Thus, those who drink mostly soft water incur an increased risk of heart disease, stroke, and hypertension, for people being treated for these conditions tend to have lower levels of magnesium in their blood.

Which one of the following, if true, most undermines the researcher’s argument?

(A) Magnesium deficiency is not uncommon, even in relatively prosperous countries with an otherwise generally adequate diet.
(B) Magnesium is needed to prevent sodium from increasing blood pressure.
(C) As people age, their ability to metabolize magnesium deteriorates.
(D) The ingestion of magnesium supplements inhibits the effectiveness of many medicines used to treat high blood pressure and heart disease.
(E) Compounds commonly used to treat hypertension and heart disease diminish the body’s capacity to absorb and retain magnesium.

“Researcher: Hard water contains more calcium and magnesium”- is a GMAT Critical question. To answer the question, a candidate can either find a piece of evidence that would weaken the argument or have logical flaws in the argument. GMAT critical reasoning tests the logical and analytical skills of the candidates. This topic requires candidates to find the argument's strengths and weaknesses or the logical flaw in the argument. The GMAT CR section contains 10 -13 GMAT critical reasoning questions out of 36 GMAT verbal questions.

Answer: (E)
Explanation: The first premise states that hard water contains more calcium and magnesium than soft water in the first sentence. The second premise, which can be found in the final two lines, claims that people who are receiving treatment for heart disease, stroke, or hypertension typically have lower blood levels of magnesium. The conclusion is that people who primarily drink soft water have a higher risk of heart disease, stroke, and high blood pressure.

This appears to be a correlation-thus-cause error. The underlying assumptions suggest a connection between low blood magnesium levels and receiving medical treatment for particular diseases. But this does not imply that certain diseases are brought on by low blood magnesium levels. In fact, it's entirely possible that both the diseases and low blood magnesium are caused by the same third factor (perhaps living near a power plant). This reasoning is illogical in every way.

The question called for an answer that refuted the researcher's stance. Finding the correct answer will be aided by carefully examining each question separately.

Option – A: Incorrect
Even though magnesium deficiency is fairly common, that does not mean that diseases aren't brought on by it. This is not the one.

Option – B: Incorrect
If accurate, this could support the case because it shows how low blood magnesium levels can result in illnesses. So, this option is also eliminated.

Option – C: Incorrect
If aging lowers blood magnesium levels and aging increases disease risk, this might weaken the argument. The only issue with this is that it is unclear whether a poor metabolism would result in low blood magnesium levels or high blood magnesium levels. Therefore, this option may either strengthen or weaken. So this is also out.

Option – D: Incorrect
This simply mixes all the ideas up, making it unclear what it would logically mean. Magnesium supplements should not interfere with your heart medication if you already have heart disease. Therefore, this is likely unimportant.

Option – E: Correct
It is possible that the medications that people take to treat their illnesses will also cause the diseases that lead to low blood magnesium levels. If so, the correlation may have a different cause and effect relationship than the argument suggested. Thus, this weakens the argument and is the right option.

From the explanations given above, it is clear that the final option stands as the correct answer.

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