Because the scientific method can go around in a circle as many times as neccisary to get the results you need
Energy that transfers through the medium
The answer, I believe, is, "B. When particles collide, no energy is lost."
Answer:
D. must have a moon
Explanation:
Scientists say that a planet must orbit a star, must be round, and must be big enough so its gravity clears its orbit of other objects. Therefore, the statement that is not a requirement for a planet is
D. must have a moon
For example, Mercury and Venus are planets with no moons.