Answer:
If a spacecraft is in space for a long time, radiation is a problem. Designers must figure out a way to protect astronauts from the radiation.
Answer:E stabilization pond
Explanation: if he lives in a tundra biome its mostly populated my swamps and ponds so that would be the most useful one.
A. the plate tectonic theory is the right answer
Anong ibig mong sabihin? (Wdym)