The map below shows kingdoms, cities, and trade routes of africa in the period 700–1600 ce. use the map to answer the following question:

the map shows africa and the surrounding oceans and seas, with historic kingdoms shown as colored in areas. dots for cities appear both within and outside the kingdoms. a series of dots runs from north to south along the coast of the indian ocean, the eastern edge of africa. lines representing trade routes crisscross the continent from city to city in a network. on the western part of the continent, several trade routes run northward from songhai through the sahara desert to north africa. on the eastern part of the continent, a single main route runs north south on the indian ocean near the coast, touching land along the way at cities such as mogadishu.

which of the following statements is supported by the map?

there was a lower volume of trade in northern and western africa, compared to the rest of the continent.

at songhai, gold was the major export, while at mogadishu slaves and ivory were.

trade routes were concentrated in the northern and western kingdoms, but trading occurred throughout the continent.

trade from mobasawa was conducted by land, while trade in kongo was conducted solely by boat.