what were the four river valley civilizations?
city-states

valley

Mesopotamian city-states

Ancient Egypt

Indus Valley

Ancient China

Explanation:

The initial four major civilization developed along river valleys. The reason for that was that these civilizations were based on agriculture, and the river valleys of the large rivers provided perfect conditions for large scale farming of crops. Three of these civilizations were in Asia and one in Africa. The ones in Asia were Ancient China along the Huang He River, Indus Valley along the Indus and Saraswati rivers, and the Mesopotamian city-states along the Tigris and Euphrates rivers. In Africa, in its northeastern part, it was the Ancient Egyptian civilization along the Nile River.

the correct answer is:   "   3.6 % " .

          →   the unemployment rate is:   " 3.6 % " .

explanation:

to calculate the "unemployment rate" :

the "unemployment rate"   =

  [# of people unemployed] /   [working age population]   * 100 %   ;

                =   [9 million] / [250 million]     *   100 % ;

    →     note:   the units of "million" cancel out;

                    since:   " {million} / {million} = 1 " ;

                =   (9 / 250)   * 100 %   ;

                = 0.036 * 100 % ;

                =   3.6 %

answer:   the unemployment rate is:   " 3.6 % " .