Question

horses evolved from a small sized mammal that ate leaves to a large grazing animal. what change occurred in the environment that led to this shift in the population? an increase in large areas of grasslands. an increase in the areas of forests. an ice age wiped out most of the forests. an increase in mountainous regions.

Explanation:

Horses evolved to be grazing animals. Grazing animals eat grass. So, an increase in grasslands (which provide grass) would lead to this shift. Forests have leaves (original food) but if there was an increase in forests, the horse might not shift to grazing. An ice - age wiping out forests doesn't directly relate to grazing. An increase in mountainous regions is not relevant to a shift to grazing.

Answer:

An increase in large areas of grasslands.