Answer: Right choice:
c. He was committed to states' rights and believed that to save the Union concessions must be made to the South.
Step-by-step explanation:
President James Buchanan tried to preserve the unity of the Union by different means but he wasn´t succesful in assuaging rising tensions North-South. He tried to prevent anti-slavery agitation in the North. He enforced the Fugitive Slave Act. Southern states began to secede in his last months in office, spurred by the victory of Abraham Lincoln in the 1860 presidential election.