According to paragraph 5, the discovery of the remains of large land animals supports the coastal hypothesis by providing evidence that A. humans were changing their hunting techniques to adapt to coastal rather than inland environments B. animals had migrated from the inland to the coasts, an indication that a midcontinental ice-free corridor was actually implausible C. humans probably would have been able to find enough resources along the coastal corridor D. the continental shelf was still exposed by lower sea levels during the period when the southward migration of people began