What is one of the techniques to improve communication?

muslims have taken his goods and products to different parts of asia an indonesia. sometimes just traveled and trade, but in other occasions, stayed in the place and made a living.

trade was the key for muslims economies to prosper. their commerce routes reached far places like malaysia and java in the 11th century.

another important factor for prosperity was that muslim states served as the middle point for european traders.

they used to travel by land but sailing the seas -the indian ocean- really increase the exportation of products.

could you show the options for the answers? : )