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 collaborative project developed by 15 initial partner nations (later expanded to 16 total) through space agency partnerships, not the UN, just the US, or 20 nations.

Answer:

D. sixteen nations.