Which strengths belonged to the north at the start of the civil war? cotton to trade for goods and weapons manufacturing that produced over 90 percent of the nation's shoes, cloth, and firearms more trained military officers more military colleges?

Answer is: manufacturing that produced over 90 percent of the nation's shoes, cloth, and firearms.
While the North was Industrial based (strong commercial and manufacturing economy), the South was predominantly agricultural with very little industry. The North produced 32 times more firearms than the South.