One important connection between the economic systems of the north and south in the same period

d. it adversely affected american productivity

true

explanation:

in 1862, president lincoln's emancipation proclamation opened the door for african americans to enlist in the union army. although many had wanted to join the war effort earlier, they were prohibited from enlisting by a federal law dating back to 1792.

explanation:

roosevelt believed that in light of the country's recent military successes, it was unnecessary to use force to achieve foreign policy goals, so long as the military could threaten force. this belief, and his strategy of “speaking softly and carrying a big stick,” shaped much of roosevelt's foreign policy.