Given a scientific question, generate a correct answer to it.

[EX Q]: What did darwin call the evolutionary concept of change in populations over generations?
[EX A]: descent with modifications

[EX Q]: Orbiting at a fairly typical 370 kilometers, the international space station is an example of what?
[EX A]: manmade satellite

[EX Q]: What returns blood from capillaries to an atrium?
[EX A]:
veins