Why doesn’t a rocket in space need to use its engine to keep it moving??? Please help!

Every action produces an equal and opposite reaction. When a rocket shoots fuel out on end, this will propel the roclet forward and no air is required. Roclets do not stop and neither do spacecrafts but they do reduce their speed. Objects will slow down in space but they won't necessarily stop. So the answer to your question is once the rocket is launched from Earth, it will have other substances to keep it moving.

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answer; i believe that the correct answer is (d) a very small amount of mass