What factors caused colonist to decide to use african slaves?

Which of the following episodes led to widespread charges that president reagan was not in adequate control? a. the u.s. retreat from lebanon after the bombing deaths of 241 u.s. marines as they lay sleeping in their barracks near beirut b. the trading of arms for hostages and the illegal funding of a right-wing insurgency in the iran-contra affair c. the sale of millions of acres of public lands to private corporations by the department of interior d. the proposal to congress, year after year, of federal budgets with huge deficits that ultimately ended up tripling the national debt

The mongols were descendants of a. pastoral nomadic tribes b. tibetan tribes c. shang nobility

How did louis sullivan and william jenney change the face of american cities in the late 1800s