Question

a researcher notices that elephants seem to communicate with one another over long distances. when the elephants are communicating, the researcher cannot hear any sounds. the researcher hypothesizes that the elephants are making subsonic sounds that humans are unable to hear. how might the researcher test this hypothesis?

• use trained dogs to detect subsonic sounds to observe how they respond to elephants communications.
• send out a variety of subsonic sounds to observe how the elephants respond.
• cover the elephants ears and observe how they behave around other elephants.
• stand close to elephants in order to hear the communication between them.

Explanation:

To test if elephants use subsonic sounds for communication, the method should directly target detecting or interacting with subsonic signals. Trained dogs can detect subsonic sounds humans cannot, so using them to sense the elephants' communications would verify if such sounds exist. Other options either don't target subsonic sounds (covering ears, standing close) or test response instead of detecting the hypothesized sounds (sending subsonic sounds).

Answer:

Use trained dogs to detect subsonic sounds to observe how they respond to elephants' communications.