The answer is D or the fourth option.
“We are at the end of our string. There is nothing more we can do.
The Kansas-Nebraska Act<span> was passed by the U.S. Congress on May 30, 1854. It allowed people in the territories of </span>Kansas<span> and</span>Nebraska<span> to decide for themselves whether or not to allow slavery within their borders. The </span>Act<span> served to repeal the Missouri Compromise of 1820 which prohibited slavery north of latitude 36°30´.</span>
