Question

The main reason for the presence of mammoth ice caps at the poles of the earth is

Answer 1

The main reason for the presence of ice caps at poles of the earth is " access to low solar energy or solar radiations".
Because these ice caps are present  very away from the equator so the solar radiation don't fall directly on that  polar region . 
Also, the polar region is high-altitude region due to which access to sunlight energy are more minimized to that area. So these areas are more cold due to the lower surface temperature .