It was once believed that cells grown in laboratory tissue cultures were essentially immortal. That is, as long as all of their needs were met, they would continue dividing forever. However, it has been shown that normal cells have a finite reproductive limit. A human liver cell, for example, divides 60 times and then stops. If such a cell divides 30 times and then is put into a deep freeze for months or even years, it "remembers" where it stopped dividing. After thawing, it divides another 30 times -- but no more. If the information above is accurate, a liver cell in which more than 60 divisions took place in a tissue culture CANNOT be which one of the following? ['a normal human liver cell that had been frozen after its first division and afterward thawed', 'a normal liver cell that came from an individual of a nonhuman species and had been frozen after its first division and afterward thawed', 'a normal cell that came from the liver of an individual of a nonhuman species and had never been frozen', 'an abnormal human liver cell']