Question ID:PT1 S4 Q3 Passage:In 1860 Bavarian quarry workers discovered the impression of a feather in a limestone slab dating to the Mesozoic era. It had previously been assumed that birds developed only after the close of the Mesozoic era and after the disappearance of pterosaurs, a species characteristic of that era. But there in limestone lay the imprint of a fully aerodynamic, three-inch-long feather. This, therefore, must have been the earliest bird—certainly, the earliest found to that date. Stem:The argument assumes which one of the following? Correct Answer Choice:CChoice A:The creature to which the feather belonged was a descendant of the pterosaurs. Choice B:Birds with such feathers were preceded by species of birds with less-developed feathers. Choice C:In the Mesozoic era, no creatures other than birds had such feathers. Choice D:The feather belonged to a Mesozoic creature that was neither a pterosaur nor a bird, but an intermediate between them. Choice E:The earliest bird flew in an awkward manner.