The Upward-Sloping Long-Run Supply Curve for Cotton Mini-Case shows a supply curve for cotton. Discuss the equilibrium

Question:

The “Upward-Sloping Long-Run Supply Curve for Cotton” Mini-Case shows a supply curve for cotton. Discuss the equilibrium if the world demand curve crosses this supply curve in either (a) a flat section labeled Brazil or (b) the following vertical section. What do cotton farms in the United States do?