Question

Which of the following led to the most sectional strife over slavery in the first half of the 19th century?
the election of Andrew Jackson
the Missouri Compromise
the raid on Harper’s Ferry
westward expansion
the Dred Scott case

Answer 1

The answer has to be A , my reason being is that Andrew Jackson has so many awards for being a hero and helping everyone. Andrew didn't like slave in the same way as everyone else did. He seen something way different , he wanted to free them, although president Lincoln did help with most of the work when he actually freed them.

Answer 2

Based on the requirement that the event happened in the first half of the century you must eliminate Dred Scott and Harper' Ferry. The events happened in 57 and 59 respectively.
The Missouri Compromise was the culmination of the strive over slavery that went through the country starting about 1817. So rather than leading to strife it sought to calm the strife.
Westward expansion led to the strife before the Missouri Compromise.
This is how that worked. People move west and settle. They want to become a state.
Slave states and Free states were equal in number. Every new state was scrutinized for how it would affect the balance in Congress, especially the Senate. If the South could be outvoted, Congress could easily pass anti-slavery laws. So the MC in 1820 worked out a way for things to stay even, for awhile.

The strive started up again after the election of Jackson in 1828. He was a slave owner from a slave state. His VP was John C Calhoun of South Carolina. Calhoun is probably the most notorious defender of slavery in our history.
Abolitionist were inspired to work harder at getting rid of slavery. The strive started getting as bad as 10 years earlier.
Northerners were sending their anti-slavery stuff through the mail to slave states. Slavers attempted to keep that literature out of the mail.
Then the whole Texas thing became part of the problem. Texas was settled by slave owners. They were their own country for a bit, but statehood was always a possibility.

The Texas issue is really the western expansion problem. I would contend the western expansion was at the heart of the slavery strife. If the nation had stayed the same size, it likely would have just moved away from slavery as it modernized.

Your milage may vary.