The irrigation of lowland river valleys has decreased the fresh water flowing into the caspian sea which in turn has caused a reduction in__

d. Fish

Explanation:

The Caspian Sea is between Europe and Asia, its resources are disputed by five different countries; Azerbaijan, Kazakhstan, Turkmenistan, Russia, and Iran. Among the disputed resources is fish.

The Caspian Sea is rich in sturgeon, fish from which caviar is obtained, but every year freshwater dismonition has unbalanced the ecosystem, as well as overfishing, leading to sturgeon becoming increasingly scarce.

I hope this information can help you.

answer; ///i believe )

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]