How do surface currents differ from deep ocean currents? Deepwater currents are dependent on the wind and landmasses. Deepwater currents are dependent on temperature and salinity. Deep ocean currents are affected by salinity and wind. None of the above​

surface currents are caused by winds : deep water currents are caused by difference in water density.

I guess the answer of your question is this

he would use the colour black

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.

if it's not useful, feel free to report for mistake in answer.