Many bird and reptile species use hissing as a threat device against potential predators. The way these species produce hissing sounds is similar enough that it is likely that this behavior developed in an early common ancestor. At the time this common ancestor would have lived, however, none of its potential predators would have yet acquired the anatomy necessary to hear hissing sounds. Which one of the following, if true, most helps to resolve the apparent discrepancy in the information above? ['The production of a hissing sound would have increased the apparent body size of the common ancestor of bird and reptile species.', 'Like its potential predators, the common ancestor of bird and reptile species would have lacked the anatomy necessary to hear hissing sounds.', 'The common ancestor of bird and reptile species would probably have employed multiple threat devices against potential predators.', 'The use of hissing as a threat device would have been less energetically costly than other threat behaviors available to the common ancestor of bird and reptile species.']