The winter is caused a. direct sunlight striking earth. b. earth's closeness to the sun. c. earth's far distance from the sun. d. indirect sunlight striking earth.

I agree with C that winter is mainly due to earth's far distance from the sun but the reason is that with the earth's elliptical orbit which takes 365 days to complete at times it is farther away from the sun so receives less warmth especially in the temperate zones.