Which action contributed to the Southern belief that their economy was threatened?

The use of old technologies and avoid improvement in the technology.

Explanation:

The use of old technologies and avoid improvement in the technology are the action contributed to the Southern belief that their economy was threatened. The smaller industrial base, fewer rail lines, and an agricultural economy based upon slave labor are the factors that is responsible for the weak economic condition of the Southern states as compared to north which had big industries and advance machinery for agriculture that make their economy strong.

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