PrepTest 110

Incorrect. While the argument establishes only that beneficial viruses can become deadly with some changes, that certainly leaves open the possibility that the opposite happens, so this answer can be true. It's also a some answer, making it likely wrong, as we discussed in our anticipation.

Incorrect. Since these other organisms aren't discussed, this certainly could be true of them. The closest the stimulus gets to discussing this is stating that the simple structure of viruses allows a few alterations to make a virus deadly, which, if anything, suggests that more complex organisms would be at most as likely as viruses to undergo these mutations ("no more likely"). It's also a some answer making it likely wrong as we discussed in our anticipation.

Incorrect. Viruses have beneficial effects, but there's nothing preventing more complex microorganisms from also having beneficial effects. It's also a some answer, making it likely wrong, as we discussed in our anticipation.

Incorrect. Killing other deadly viruses is one example of a way in which viruses can be beneficial to humans, so it's possible that there are other ways, and viruses which help humans only through those ways. It's also a some answer, making it likely wrong, as we discussed in our anticipation.

Correct. Argument or Facts:
Facts

Question Type:
Cannot Be True

Stimulus Summary:
Science. A lot of weak statements ("can" "some").
Any virus can easily become dangerous.

Answer Anticipation:
Yes our Summary is a bit ridiculous. However there's no way you have the time (or likely background) to really dig in and make sense of all of this. Instead we should focus on what we know about Cannot Be True questions. Mainly that the correct answer has to contradict the stimulus.

As such we can look at all of those weak statements and know that to contradict them the correct answer would have to be strong—you can't contradict a some statement with another some statement. The one exception is the last statement—"any" virus can easily become dangerous to humans—and so we noted that one as it's the only one strong enough to be contradicted by a some statement.

Beyond that it's likely a waste of time to try to anticipate anything or digest this stimulus more. Let's head into the answers to find something that's contradicted.

Answer Explanation:
The second sentence notes that some viruses kill "more—complex" microorganisms that are deadly to humans thus benefiting humans. As such there are some viruses deadly to organisms of greater complexity than itself—the ones deadly to humans—that are beneficial to humans contradicting this answer. This is therefore the correct answer. (Note also that it's the strongest answer—and that's generally the correct answer in a Cannot Be True question since such a categorical statement is unlikely to be true.)

Key Takeaway:
Cannot Be True questions are about contradictions. Weaker statements are harder to contradict; stronger statements are easier to contradict. As such focusing on strong statements in the stimulus and stronger answer choices will usually allow you to find the correct answer faster.