White-crowned sparrows can only learn the “crystallized” song for their species by A) listening to adult sparrow songs during a sensitive period as a fledgling, followed by a practice period until the juvenile matches its melody to its memorized fledgling song. B) listening to the song of its own species during a critical period so that it will imprint to its own species song and not the songs of other songbird species. C) practicing as a fledgling until the innate species-specific song becomes perfected. D) performing the crystallized song as adults when they become sexually mature, as the song is programmed into the innate behavior for the species. E) observing and practicing after receiving social confirmation from other adults at a critical period during their first episode of courtship behavior.