The key idea in a specific excerpt is that Grady believes what is necessary for the South?

Grady's key idea is that the South needed to industrialize, which reflects his vision of transforming the Southern economy from primarily agricultural to more diverse and industrialized. In the late 19th century, many Southern leaders advocated for this shift in order to modernize the region and improve its economic viability following the Civil War. Grady, in particular, highlighted the importance of developing manufacturing and infrastructure as a means to create jobs, attract investment, and elevate the South's economic status in comparison to the more industrialized North. This perspective was rooted in the belief that embracing industry would help the South recover from the devastation of the war and ensure its competitiveness in the national economy.

The other options pertain to different economic philosophies or strategies that were less aligned with Grady's vision. Remaining purely agricultural would not address the economic challenges the South faced. Adopting socialism did not resonate with Grady's support for capitalism and individual enterprise. Relying on Northern support was not sustainable in the long term, as Grady sought to promote self-sufficiency through local industrial growth. Therefore, industrialization stands out as the crucial element in Grady's proposal for the South’s future.