Analysis of test questions: This question examines the price of commodities. Point A is wrong. At point A, the price of pork rises, its demand drops, and the demand for its substitutes increases. Point B is in line with the meaning of the question. Point B, the price drops, indicating that pork is in oversupply and is in a buyer's market. Point C is wrong. During the period from point A to point B, the price drops and the profit decreases, which should be to reduce production, so resources will flow out of the pig industry. Point D is wrong.

Comments: The price of goods is determined by value, but affected by the relationship between supply and demand, price changes will affect people's purchasing power and thus affect commodity consumption. When the price of a commodity goes up, people will buy less of it, and when it goes down, they will buy more of it. Changes in commodity prices cause changes in the demand for the commodity in the opposite direction. The difficulty is moderate.