Plz help Which group of historical events had the most to do with abolition?

The Fugitive Slave Act, the Dred Scott decision, and the Kansas-Nebraska Act
The Compromise of 1850, the Mexican-American War, and the Gadsden Purchase
The annexation of California, the Anthony Burns case, and the Harper's Ferry revolt
The Louisiana Purchase, the Missouri Compromise of 1820, and the annexation of Texas

Fugitive slave act, dred Scott decision, and the Kansas Nebraska act

Explanation:

correct me if I'm wrong

the perimeter of a triangle is 69 cm. side a is 5 cm shorter than side b. side c is twice as long as side a. find the length of each side. i need to know how to do it in 2 equations.  

equations:

a = b-5

c = 2a

a + b + c = 69

most people now work in jobs where they do one  kind  of work; they are carpenters, bankers, cooks, mechanics, and so forth. likewise, most  businesses produce  only certainkinds  of  goods  or  services, such as cars, tacos, or gardening  services. this feature of  production  is known as specialization.