Which made it possible for mongol armies to conquer chinese wall cities
a. mongol archers on horseback
b. cannons and other new weapons
c. mongol spies and siege engines
d. famine and civil war inside china

2. a land bridge connected asia and north america thousands of years ago.

4. crossing the land bridge would have been simple for the first migrants.

5. people might have crossed a land bridge while hunting animals.

a plantation economy is an economy based on agricultural mass production, usually of a few commodity crops grown on large farms called plantations. plantation economies rely on the export of cash crops as a source of income.

i hope this : )