Question

tensions rise
the ____ __ allowed california to enter the union as a ____ state. other territories acquired by the united states could decide for themselves whether they would allow slavery.
under the ____ ____, people in each state would be able to vote on whether to allow slavery.

Explanation:

For the first blank (red box), the Compromise of 1850 allowed California to enter as a free state. For the second blank (green box), the concept of popular sovereignty (under the Kansas - Nebraska Act or related to the Compromise of 1850's application to other territories) let people in each state/territory vote on slavery. So the first blank should be "Compromise of 1850" and the second blank should be "popular sovereignty".

Answer:

First blank (red box): Compromise of 1850
Second blank (green box): popular sovereignty