When communicating with Apollo astronauts, scientists on Earth use radio waves and the "over to you" method of communication. This method must be used because of the delay in communication. This delay is due to the

metals are good conductor of electricity. it has free electrons on their surface. according to electron pool theory, each atom present in a metal crystal losses all of its valence electron and as a result a pool of free is form. these pool of electrons are free to move and   conduct electricity easily   while making metal as good conductor.

the correct answer is a. the ability of electrons to flow throughout the metal.

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