Final answer:
The first sentence highlights the South's awareness of their disadvantage against the North, yet underlines their eagerness to preserve their slave-based economy, leading to the Civil War.
Step-by-step explanation:
The first sentence of the paragraph serves to set the stage for an understanding of the challenges and perspectives that led to the American Civil War, focusing particularly on the viewpoint of the Southern states. It explicitly states the demographic and economic disadvantages the South faced in comparison to the North, acknowledging the South's awareness of this but simultaneously showing their resolution to maintain their social and economic system. The sentence outlines the stakes of what the South was risking and implies that their commitment to their way of life, which was fundamentally linked to slavery and an agriculturally-dominated economy, was so intrinsic that these states were willing to face the material disadvantages in an attempt at secession.
The correct response to the student's question is option A, as the sentence emphasizes what the South was willing to risk to preserve their cotton- and slavery-based economy, which is central to understanding the motivations behind the secession of Southern states and the ensuing Civil War.