Which Statement About the Southern Economy in the Later 1850s

Which statement about the southern economy in the later 1850s is true?

A) A sense of crisis grew in the region as the price of slaves rose sharply.
B) The progress of transportation development reoriented western trade toward New Orleans.
C) Although cotton's importance as an export crop declined, it remained the primary driver of domestic economic growth.
D) As they converted to the new agricultural machinery, southern planters found themselves deeply in debt in a time of declining profits.