Which factor may begin an ice age? select all that apply

Fluctuations in the amount of insolation (incoming solar radiation) are the most likely cause of large-scale changes in Earth's climate during the Quaternary. In other words, variations in the intensity and timing of heat from the sun are the most likely cause of the glacial/interglacial cycles. 

We are not able to see the stars. light prevents our seeing the stars. i hope it kinda : )