Question

very cold periods in earths history resulted in which of the following?
tree rings
deposits of pollen
glaciers
sunspots

Explanation:

Tree rings are formed due to seasonal growth changes in trees, not directly by very cold periods. Deposits of pollen are related to plant reproduction and sedimentation. Sunspots are on the Sun and not a direct result of Earth's cold periods. Glaciers form when snow accumulates over time and compresses under cold conditions.

Answer:

glaciers