Question

the missouri compromise dealt with
a the admission of california and missouri to the union.
b the expansion of slavery into the former louisiana territory.
c the slave trade in washington, dc, and the return of runaway slaves.
d the right of states to negotiate their own trade agreements with foreign nations.

Explanation:

The Missouri Compromise (1820) was a federal agreement focused on regulating slavery's spread in the U.S. It admitted Missouri as a slave state, Maine as a free state, and banned slavery in the former Louisiana Territory north of the 36°30' parallel. Option A is wrong because California was admitted later via the Compromise of 1850. Option C refers to provisions of the Compromise of 1850, not 1820. Option D is unrelated, as states never had the right to negotiate foreign trade agreements under U.S. federalism.

Answer:

B. the expansion of slavery into the former Louisiana Territory.