Why are there no samples of rocks from the early Precambrian era? O A. They have undergone metamorphosis.
O B. They are buried under sediment.
O C. All of them formed under volcanoes.
O D. All rocks were molten in that time period.

Fossils of ancestors of the modern horses show a small 4-toed almost dog-like browsing animal named eohippus over time the horses got larger lost toes and changed to a grazing diet what is the best explanation of why this change occurred