Final answer:
The question asks what would be different about Earth and its moon if you could return in many millions of years. The orbital period of the moon would be different due to it moving away from Earth, and the length of the year might also see minor changes. Other aspects, like moon phases and Earth's seasons, would be relatively similar unless axial tilt or orbital dynamics substantially change.
Step-by-step explanation:
If you could somehow return to the Earth in many millions of years, you would likely notice changes in the length of time it takes for the moon to orbit Earth (option c). The moon is gradually moving away from Earth, which will cause its orbital period to increase slowly over time. The length of the year (option a) might also experience some minor changes due to gravitational interactions with other bodies in the solar system, though this change would be subtle over such a timescale.
As for the fact that the moon shows phases (option b), this is a consequence of its orbit around Earth relative to the position of the sun, and as long as these dynamics are in place, we would expect to see moon phases. However, the phases themselves might look subtly different due to the changing orbital characteristics. Lastly, if Earth's axial tilt remains unchanged, the fact that the Earth has seasons (option e) would likely remain the same, though the specifics of how we experience seasons could be influenced by changes in Earth's orbit, the amount of land vs. water distribution, and climatic factors.