According to paragraph 5, which of the following statements is true about white-crowns reared in isolation that are exposed to tapes of other species' songs A. The tapes cause the white-crowns to begin singing earlier than those not exposed to the tapes. B. The tapes do not affect the white-crowns' singing development or change their song. C. The tapes help the white-crowns learn the standard song of their species. D. The tapes aid the white-crowns in learning local dialects of other species.