They wanted to gain more wealth in the future profit, therefore the answer is D.
The Southern states were not ready for a republican president. Especially one who raised some serious questions.
Also prior to his election the southern states had already threatened to secede.
Hope this helps.
South Korean Multinational Enterprises and Vietnam SMEs’ Participation in Global Production Networks in the Context of Increased ASEAN and East Asian Regional Economic Integration.
C. hunting plants and animals became the source of food.