A．To point that the Botai people sometimes did not have enough food.
B．To compare the physical features of domesticated and wild horse.
C．To prove that the horses of the Botai people were domesticated.
D．To emphasize that horse milk was popular in some ancient societies.

A．They do not reveal information about horse domestication.
B．They are very different from the bones of modem horses.
C．They date to the period when the Botai people had become moving about.
D．They suggested that horses were first domesticated by another ancient people.

A．They found a way to protect livestock from harsh weather in their regions.
B．They realized that a moving lifestyle offered benefits that outweighed the hard work.
C．They had to learn the area due to a rapid increase in population.
D．They learned that growing crops is possible in the southern regions.