Answer:
e)Mongols
Explanation:
Horse-human relationship has a long history where it evolved from the state where horses were just looked for meat to their domestication. But with the invention of stirrup and saddle about 2000 years ago China has completely altered the use of horses. Now they were used in warfare as they provide greater mobility and supported mounted archers. This became one of the most striking features of Mongols who have controlled the largest empire in the history of mankind.