The natural barriers of this River Valley Civilization included the Himalaya Mountains and large deserts, but no natural barrier in the north (which made them build a wall as a barrier).
Your answers
Mesopotamia
Egypt
China
India

Rational ignorance suggests that a. voters are ignorant on issues that are not of special interest to them b. voters do not pursue information about issues before voting c. low voter turnout is due to a lack of understanding of the platforms of each political party d. voters are uninterested in the electoral process