In 1854, the issue of slavery was inflamed by the Kansas-Nebraska Act. Option B is correct.
On May 30, 1854, the U.S. Congress passed The Kansas-Nebraska Act. It allowed people in the territories of Kansas and Nebraska to decide for themselves whether or not to allow slavery within their borders. The Act was used to repeal the Missouri Compromise of 1820 which forbade slavery north of latitude 36°30´.