Answer:
The answer is likely B.
Step-by-step explanation:
I said B, however, the wording is strange. It says "low" solar activity - ...the sun doesn't turn off - but the amount of solar radiation reaching earth can vary. A is eliminated, because there were no cars to consume Fossil fuels during the Pleistocene Age - and the earths orbit did not shift any more particularly that its already tilted axis - eliminating C. The break up of a landmass would not necessarily cause global cooling either. Leaving us with B.