TOEFL Listening: ETS-TOEFL听力机经 - 05N93FMHG3P6Z81YP$

According to the professor, what is a question that the researchers are investigating? A. How manatees' navigational abilities compare to those of whales and dolphins B. How changes in water visibility can affect manatees' ability to navigate C. Whether manatees can detect motionless objects in water D. Whether manatees can remember specific routes to food source