Wrong flaw. This introduces a new term in the conclusion—health problems—that is not in the premise, about which we therefore cannot draw a valid conclusion. That isn’t the same flaw from the stimulus, though, which confuses “many” for “all” and the sufficient condition for the necessary condition.

Wrong flaw. This gives us a historical fact about the most famous opera singers and then uses it to draw a conclusion about a relationship between two opera singers about whom we have insufficient information—we don’t know how often Franz practices! And maybe Otto won’t be the most famous, but he could still be more famous than Franz without practicing! That isn’t the same flaw from the stimulus, though, which confuses “many” for “all” and the sufficient condition for the necessary condition.

Wrong flaw. This introduces a new term in the conclusion—greatly enjoying the opera—that is not in the premise, about which we therefore cannot draw a conclusion. That isn’t the same flaw from the stimulus, though, which confuses “many” for “all” and the sufficient condition for the necessary condition.

Wrong flaw. This assumes that correlation proves causation. The fact that George might carry a bent nail for good luck and the fact that he also is a lucky person does not prove that his (possibly extant) bent nail causes his luck! That isn’t the same flaw from the stimulus, though, which confuses “many” for “all” and the sufficient condition for the necessary condition.

The argument starts with a “some” relationship: many successful opera singers studied more than one language. On that basis, it concludes that a person who studied more than one language must be a successful opera singer. This commits the same sufficient vs. necessary condition and some vs. all flaws as the stimulus by assuming that, because many successful opera singers studied more than one language, all people who studied more than one language must be successful opera singers.