I think that the answer is C.)
It makes the most sense because one or two of the other options talk about the sun getting closer to the earth which makes no sense. Also, the Earth's spinning speed does not slow down so that rules out option B. Lastly, the answer cannot be A whereas the sun's light does not fade, rather the Earth spins with a shadow casting over its back due to no sunlight on that facing side.
Hope this helps and have a nice day.
-R3TR0 Z3R0