Question

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.

Explanation:

The International Space Station (ISS) is a habitable artificial satellite in low - Earth orbit. It was built as a joint project involving sixteen nations. These include the United States, Russia, and several European, Japanese, and Canadian space agencies.

Answer:

D. sixteen nations