Astronauts and scientists conduct research studies aboard the international space station, a satellite that was built by the united nations. the united states. twenty nations. sixteen nations.

D) Sixteen nations

Explanation:The correct answer from the choices above is option D. Astronauts and scientists conduct research studies aboard the International Space Station in a satellite that was built by sixteen nations.

Sixteen Nations

Explanation:

in 550 b.c.e. cyrus the great, the leader of the persians, conquered the medes and united the iranian people under one ruler for the first time. cyrus became the first king of the persian empire and went on to establish one of the largest empires in world.