Test analysis: this question examines the price of goods. Point a is wrong. At point A, the price of pork rises, the demand drops, and the demand for its substitutes increases. Point b fits the question. At point B, the price drops, indicating that pork supply exceeds demand and it is in the buyer's market. Point c is wrong. During the period from point A to point B, prices drop and profits decrease, which should be a reduction in 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, thus affecting commodity consumption. When the price of a commodity rises, people will buy less, and when the price falls, they will buy more. The change of commodity price causes the demand for this commodity to change in the opposite direction. The difficulty is moderate.