According to paragraph 2, researchers discovered which of the following by playing recordings of songs to chaffinches? A. Chaffinches could no longer be taught to reproduce sounds after the first few weeks of life. B. Chaffinches could not reproduce songs with exactly the same patterns of recorded songs. C. Chaffinches at the age of eight months could recall and reproduce a song that they heard in the first few weeks of life. D. Chaffinches that learned a song from recordings in the first few weeks of life were later unable to copy the sounds of mature chaffinches.