The greatest obstacle that Columbus and other European merchants encountered in their attempts to enter the Asian market:. a. the Muslim middlemen
b. the Eastern Orthodox Church
c. widespread corruption and warfare
d. the dictates of the Pope in Rome

d. stage 4

explanation:

the existence of some kind of demographic transition is widely accepted in the social sciences because of the well-established historical correlation linking dropping fertility to social and economic development.[1] scholars debate whether industrialization and higher incomes lead to lower population, or whether lower populations lead to industrialization and higher incomes. scholars also debate to what extent various proposed and sometimes inter-related factors such as higher per capita income,lower mortality, old-age security, and rise of demand for human capital are involved.[2]

niger

explanation:

bc its the main river

моля да ми помогне с английски език аз не разбирам

molya da mi pomogne s angliĭski ezik az ne razbiram