GMAT Critical Reasoning (CR) | Re: Sheila: Health experts generally agree that

let us simplify the argument given-

Sheila
Smoking tobacco for many years --> very likely to be harmful to smoker'shealth

Tim
Grandfather smoked 3 cigars a day from age 14 + lived up to 96 years --> Smoking has no effect at all

Immediately, we see a problem with Tim's reasoning. He tries to negate Sheila's conclusion by providing a single counterexample(there might be hundreds of thousands of people who might have suffered severe consequences to their health after smoking). Tim makes
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