The only possible answer to this question is D, that Zheng He carried out voyages of exploration.

As the link below shows, Zheng He was an explorer and an admiral.  He was actually a Muslim who came from the province of Yunan.  His family must have been at least well to do because both his grandfather and his father had made pilgrimages to Mecca.  As it happens, Zhen He was a eunuch.

Zheng He's seven voyages (which took place beginning in 1405 and ending in 1433) took him as far as the Persian Gulf and the East Coast of Africa.  These voyages were made possible by advances in Chinese technology in the areas of navigation and shipbuilding.