Loggerhead sea turtle hatchlings must navigate across vast oceans immediately after birth. Biologist Kenneth Lohmann investigated whether this navigation is a learned behavior or an innate capability utilizing the Earth’s magnetic field. His team placed distinct groups of hatchlings, which had never been in the ocean, into water tanks surrounded by magnetic coils that simulated magnetic fields found in different geographic locations. The hatchlings consistently swam in the direction that would keep them within safe currents in the wild, suggesting that ______
Which choice most logically completes the text?
sea turtles likely learn navigational cues from older turtles during their first migration.
the magnetic field of the Earth is the only navigational tool used by marine reptiles.
the ability to interpret magnetic fields for navigation is an instinctual trait present from birth.
hatchlings are unable to detect magnetic fields until they reach a certain stage of maturity.
Correct Answer: C
Choice C is the best answer. The text describes an experiment where hatchlings that had never been in the ocean successfully navigated using simulated magnetic fields. Since they had no opportunity to learn this, the behavior must be "instinctual" or innate.
Choice A is incorrect because the hatchlings in the experiment had no contact with older turtles, ruling out social learning. Choice B is incorrect because the experiment only tested magnetic fields; it does not prove this is the only tool they use (they might also use sunlight or wave direction). Choice D is incorrect because the hatchlings did respond to the fields in the experiment, contradicting the idea that they are unable to detect them.