Which socioeconomic class grew the fastest under manifest destiny?

upper class

middle class

lower class

working class

The socioeconomic class which grew faster under the manifest destiny was the working class.

Explanation:

Farmers increased their yields and sold their products to other foreign markets. Farmers started to rely totally on c ash and credit purchase rather than bartering. They began to deal with merchants and middlemen rather than taking the harvest directly to the marker and selling it.  

Textile mills was the first type of factory set up established during the manifest destiny period. Cotton refine mills and manufacturing divisions were the source of income for the middle and the working class people. Workers became employees. Farm owners became the mill owners.

the answer is