A major difference between the North and the South was a)The South was needed slaves for the cotton fields and the North needed slaves for their factories. b)The North was becoming industrialized, while the South remained agrarian (farm-based). c)The North's climate didn't allow cotton to be produced, so they didn't have slaves.

b)The North was becoming industrialized, while the South remained agrarian (farm-based).

Explanation:

The northern states of the USA had a strong industrialization and were the main responsible for supplying the country with industrial pipelines, in addition to having a concentration of industries, machines and free workers, since industries did not adopt slave labor. However, a country needs agricultural products to maintain itself and this production was the responsibility of the southern states, which had a strong agrarian nature and supplied the country with this type of production. Farming work required a great deal of cheap labor and for that reason, these states, for the most part, used slave labor.

i think it is the third one.