What does voluntary destination mean ? ?

How does the map develop the central idea that scholars at jundi shapur spread the knowledge of sugar? the map illustrates the spread of sugar from new guinea to persia. the map shows that sugar was being refined primarily in the north rather than the south. the map illustrates the spread of knowledge about refined sugar processing to egypt. the map illustrates that people in china knew how to refine sugar and shared this knowledge. the answer is c