Question

An ingredient in coffee, known as RTC, has been found to inactivate common cold viruses in experiments. In earlier experiments, researchers found that inactivated common cold viruses can convert healthy cells into cancer cells. It can be concluded that the use of coffee can cause cancer.

Which one of the following, if true, most seriously weakens the argument?

• A. Several teams of scientists performed the various experiments, and all of the teams had similar results.
• B. The carcinogenic effect of RTC could be neutralized by the other ingredients found in coffee.
• C. When RTC kills common cold viruses it weakens the immune system, and this might diminish the body's ability to fight other viruses, including viruses linked to cancers.
• D. If chemists modify the structure of RTC, RTC can be safely incorporated into medications to prevent the common cold.

Hint:

Look for the option that offers a different cause for the cancer risk, one that breaks the argument's assumed "inactivated virus becomes cancerous" chain.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
This is a weaken-the-argument question from critical reasoning. We must find the option that most damages the logical link between the premises and the conclusion, without simply contradicting a fact outright.

Step 2: Key Formula or Approach:
First write out the argument's exact chain of cause and effect: RTC inactivates the cold virus, inactivated cold viruses can turn cells cancerous (per earlier experiments), so coffee, which contains RTC, can cause cancer. A weakening answer must attack one of the links in this chain, ideally by offering a different explanation for the same outcome.

Step 3: Detailed Explanation:
Option A talks about experimental reliability across multiple teams, which supports the premises rather than attacking the conclusion, so it strengthens the argument instead of weakening it.
Option D discusses a hypothetical, chemically modified version of RTC used in future medicine, which says nothing about whether today's natural RTC in coffee causes cancer, so it is irrelevant to the argument as stated.
Option B claims other coffee ingredients cancel out RTC's carcinogenic effect. This is a reasonable weakener, but it just asserts a counteracting effect without explaining why, and offers little real insight into the actual cancer risk mechanism.
Option C reframes the entire mechanism: RTC's cold fighting action works by weakening the immune system generally, and it is this general weakening, not the specific "inactivated virus becomes cancerous" idea, that could raise cancer risk from other, pre-existing cancer linked viruses. Since this points to a completely different cause for any cancer risk, it directly attacks the argument's specific causal reasoning, making it the strongest weakener.

Step 4: Final Answer:
Option C most seriously weakens the argument, since it replaces the argument's assumed mechanism with an unrelated one, breaking the causal link the conclusion depends on.
\[ \boxed{\text{Option (C)}} \]