Antarctica (pls explain why E )

max37274 wrote:On the basis of the available evidence, Antarctica has generally been thought to have been covered by ice for at least the past 14 million years. Recently, however, three-million-year-old fossils of a kind previously found only in ocean-floor sediments were disovered under the ice sheet covering central Antarctica. About three million years ago, therefore, the Antarctica ice must temporarily have melted. After all, either severe climatic warming or volcanic activity in Antarctica's mountains could have melted the ice sheet, thus raising sa levels and submerging the continent.

The reasoning in the argument is most vulnerable to which one of the following criticisms?
a. That a given position is widely believed to be true is taken to show that the position in question must , in fact, be true
b. That either of two things could independently have produced a given effect is taken to show that those two things could not have operated in conjunction to produce that effect
c. establishing that a certain event occured is confused with having established the cause of that event
d. a claim that has a very general application is based entirely on evidence from a narrowly restricted range of cases
e. an inconsistency that, as presented, has more than one possible resolution is treated as though only one resolution is possible-Most vulnerable because they are only considering one case.MAybe the climatic effect is due to any other external sources[/b]