what most likely caused the ice ages?\no the size of tree rings and the amount of pollen grains\no solar…

Brief Explanations:

The tilt of the Earth's axis (obliquity) and the shape of its orbit (eccentricity) are Milankovitch cycles that affect the amount and distribution of solar radiation reaching Earth, which is a major factor in ice - age cycles. Tree rings and pollen grains are used to study past climates but don't cause ice ages. Solar flares and ejections have short - term effects on Earth's magnetosphere and don't cause long - term ice - age cycles. The moon's temperature has no significant impact on Earth's ice ages, and the Sun's temperature changes on very long timescales not directly related to known ice - age cycles.

Answer:

the tilt of the Earth's axis and the shape of its orbit