President who had a hard time deciding what to do as tensions rose in 1860; he made an effort to reinforce the garrison at Charleston in January, 1861, but the supply ship was fired on and driven off. This president's indecision and subsequent actions contributed to:
a) The outbreak of hostilities between the North and South
b) A diplomatic resolution to the secession crisis
c) Heightened tensions between the federal government and Southern states
d) Increased support for secessionist movements in border states