What principle did the southern states say justified leaving the union (of the United States)?

the answer is b.2008 and 2012 were presidential election years.

explanation: d

these civilizations were located around fertile rivers, where they could produce an abundance of crops

the correct answer is d. the monetary reserve is a set of funds represented in currency, money or similar, saved as a forecast of possible needs or for legal reasons.

the increase or decrease in the monetary base influences in the increase or decrease of the inflation rate. therefore, the excess of monetary reserve will cause the reduction of inflation.