In the early and mid-1800s, sectionalism was strongest

In the early and mid-1800s, sectionalism was strongest In the South, where people felt their economy depended on slavery.

Explanation:

The invention of the cotton gin in 1793 made the production of cotton more efficient and profitable, and the Southerns rely on the slaves to keep the cotton production using those machines and to increase their earnings. Many people state that the Southern economy wouldn't be that wealth if it wasn't for the slaves.

the three answers (for plato at least) are:

b-condemned sola fida 

d-set rules for establishing seminaries and for educating clerics in the seminaries 

f-recommended moderation in the sale of indulgences and banned the sale of false indulgences 

a historian researching the immigration policies of the early 1900s would expect a source written today,rather than in 1910 to :

( a ) be more interested in objective data and statistics.