## #8 - It was once believed that cells grown in laboratory

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Complete Question Explanation

Cannot Be True. The correct answer choice is (B)

Normal cells can divide only a finite number of times. Normal, human, liver cells can divide 60 times max, even if frozen then thawed.

If a given liver cell divides MORE than 60 times, then which one of the answer choices cannot be true? Pre-phrases you might think of can include: 1) it is a normal human liver cell that has never been frozen; 2) it is a normal human liver cell that has been frozen after dividing once, and thawed afterwards; 3) it is a normal human liver cell that has been frozen after dividing twice, and thawed afterwards; 4) it is a... after dividing 10 times, and thawed afterwards, etc. All of the above contradicts the stimulus because we know that normal human liver cells cannot divide more than 60 times, no matter if we freeze it or not.

This is a cannot be true question, so we're looking for an answer choice that directly contradicts something said in the stimulus, or contradicts a necessary implication of the stimulus.

Answer choice (A): This answer is incorrect because the stimulus only makes predictions about normal human liver cells' ability to divide. Abnormal human liver cells may be different and may be able to divide more than 60 times. As such, this does not contradict the stimulus, so this is wrong.

Answer choice (B): This is the correct answer choice. It is correct because it is a normal human liver cell that has been frozen and thawed after its first division (like our second pre-phrase). According to the stimulus, this liver cell would still only be able to divide 60 times, yet it somehow exceeded the maximum. Since it contradicts the stimulus, this is the right answer.

Answer choices (C), (D),and (E) are incorrect because it talks about non-human liver cells. The stimulus only makes predictions about normal human liver cells' ability to divide. As such, non-human liver cells that divide more than 60 times do not contradict the stimulus' predictions.