Which of the Following Is an Example of Partial Equilibrium

Which of the following is an example of partial equilibrium analysis?

A) A tax on Internet sales reduces the quantity of online sales and the demand for Internet access. The lower price for Internet access will spur increased demand for online sales.
B) A deep freeze has destroyed much of the orange crop, raised the price of oranges, and reduced the quantity sold.
C) Productivity enhancements in the manufacturing sector have increased wages in that sector, putting upward pressures on wages necessary to attract workers to the service sector.
D) Scientific research indicates that there are health benefits to wearing cotton. Knowledge of these benefits raises the demand for cotton and reduces the supply of corn as farmers plant more cotton.