Final answer:
Arab merchants created trade agreements to facilitate peaceful trade across regions, expanding the reach of Islam and generating economic prosperity. The correct option is C.
Step-by-step explanation:
The reason Arab merchants created trade agreements was c. to help trade take place peacefully between regions. Such agreements facilitated the exchange of commodities and ideas, thereby expanding the reach of Islam and creating economic prosperity through direct income and taxation.
Trade agreements underpinned by a shared set of religious customs, laws, and language promoted stable and peaceful relations throughout the diverse Islamic world, which extended from Spain to China, helping to maintain unity in this vast region.