Correct Answer : Option (D) - All of the above
Under Kaniska I (flourished 1st century CE) and his successors, the Kushan kingdom reached its height. It was acknowledged as one of the four great Eurasian powers of its time (the others being China, Rome, and Parthia). The Kushans were instrumental in spreading Buddhism in Central Asia and China and in developing Mahayana Buddhism and the Gandhara and Mathura schools of art.
The Kushans became affluent through trade, particularly with Rome, as their large issues of gold coins show.