Final answer:
The Kansas-Nebraska Act voided the Missouri Compromise and allowed territories to decide whether they would allow enslavement of human beings instead of letting Congress decide.
Option 3.
Step-by-step explanation:
The decision that voided the Missouri Compromise and allowed territories to decide whether they would allow enslavement of human beings instead of letting Congress decide was the Kansas-Nebraska Act.
This act, introduced by Senator Stephen Douglas in 1854, repealed the Missouri Compromise and established popular sovereignty in the Kansas and Nebraska territories.
Under popular sovereignty, the residents of each territory would vote to determine whether slavery would be allowed.