The correct answer is D, as during the early 19th century, only wealthy families had means of transportation to the north; other families were able to get what they needed within their settlements or farm areas.
The less affluent families could subsist thanks to the economic system prevailing in the South, which based its development on agricultural production. Otherwise, the subsistence of these families would have been impossible, since there were no effective means to access the products from the north quickly.
The transport system of the South was too expensive for the common people and depended mainly on fluvial and coastal traffic by ship; both were closed by the Union Navy during the Civil War. The small railroad system practically collapsed as a result of this, so that by 1864 internal travel was so difficult that the Confederate economy was mutilated.