The most commonly used source of geographical material is
-dictionary
-almanac
- encyclopedia
-readers guide

I believe the correct answer is the third one: The ENCYCLOPEDIA

the mongolian invasion of china and central asia resulted in a disruption of the silk road as the chinese garrisons lost support from the chinese kingdoms which fell under the mongols. however, as the mongols established a formal dynasty in china, the successors of genghis khan restored the garrisons along the silk road allowing the safe travel caravans again.

the answer as multiple choice is c

africa, the second-largest continent, is bounded by the mediterranean sea, the red sea, the indian ocean, and the atlantic ocean. it is divided in half almost equally by the equator. the continent includes the islands of cape verde, madagascar, mauritius, seychelles, and comoros.

africa’s physical geography, environment and resources, and human geography can be considered separately.

the origin of the name “africa” is greatly disputed by scholars. most believe it stems from words used by the phoenicians, greeks, and romans. important words include the egyptian word afru-ika, meaning “motherland”; the greek word aphrike, meaning “without cold”; and the latin word aprica, meaning “sunny.”

today, africa is home to more countries than any other continent in the world. these countries are: morocco, western sahara (morocco), algeria, tunisia, libya, egypt, sudan, chad, niger, mali, mauritania, senegal, the gambia, guinea-bissau, guinea, sierra leone, liberia, côte d’ivoire, ghana, burkina faso, togo, benin, nigeria, cameroon, central africa republic, equatorial guinea, gabon, congo, democratic republic of the congo, angola, namibia, botswana, south africa, lesotho, swaziland, mozambique, zimbabwe, zambia, malawi, tanzania, rwanda, burundi, uganda, kenya, somalia, ethiopia, djibouti, eritrea and the island countries of cape verde, madagascar, mauritius, seychelles, and comoros.

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