TOEFL Listening: TPO-TOEFL阅读TPO - 1L5P135OIVW636MHN$

According to paragraph 6, how did the birds navigate in the planetarium's nighttime environment? A. By waiting for the dome to stop rotating B. By their position on the planetarium floor C. By orienting themselves to the stars in the artificial night sky D. By navigating randomly until they found the correct orientation