Final answer:
The obstacle that slowed the production and sale of cotton was lack of demand.
Step-by-step explanation:
The obstacle that slowed the production and sale of cotton was B) Lack of demand.
During the time of the Civil War in the United States, cotton prices fell significantly as Southern cotton planters could not sell their cotton either to the North or overseas. With a lack of cotton coming from the South, overseas buyers were forced to look elsewhere for a supply. By the time the war was over, the damage was done, and cotton prices remained low.
This lack of demand made it difficult for farmers in the Cotton Belt to sell their crop at prices high enough to cover their debts, leading to a slowdown in production and sale of cotton.