The Supreme Court’s 1857 decision in Dred Scott v. Sandford had such a demoralizing effect on the efforts to end slavery because: A. The court ruled that Congress couldn’t prohibit slavery in any state and that blacks
were not citizens and therefore not entitled to Constitutional protections
B. Dred Scott was to remain a slave because he returned to Missouri
C. It allowed for more slaves to be imported into the country
D. The Civil War began the next month

i am not sure what the answer is but i am not sure if my explanation will help.

Explanation:

Dred Scott v. Sandford, 60 U.S. (19 How.) 393 (1857), often referred to as the Dred Scott decision, was a landmark decision of the US Supreme Court in which the Court held that the US Constitution was not meant to include American citizenship for black people, regardless of whether they were enslaved or free, and so the rights and privileges that the Constitution confers upon American citizens could not apply to them