Who wrote about his travels along the Silk Road and his 17-year-long stay in China?
A. The Silk Road actually refers to a series of trade routes rather than a single road.

B. Cowry shells and silk were used as forms of money along the Silk Road.

C. Trade along the Silk Road flourished under the strong protection of the Huns.

D. Ideas and technology, as well as goods, were exchanged along the Silk Road.