In this task, you are given a context and four options. Each option is a suggested ending for the context. You should read the context and pick the best ending for the context. Please answer with "A", "B", "C", and "D".
Q: [header] How to calculate consumer surplus [title] Understand the law of demand. [step] Most people have heard the phrase " supply and demand " used in reference to the mysterious forces governing market economies, but many don't understand these concepts' full implications. " demand " refers to the desire for a good or service in the marketplace. <sep> (A) [substeps] For example, " supply and demand products by frugal farmers entrepreneurs should be heavily distributed and integrated in the new market. For established " goods, whether any subsequent products upon that market must be sold within the same year. (B) Therefore, prices will rise and fall because demand for goods is increased rapidly, attracting new markets and becoming increasingly competitive. [substeps] Establish the limit of demand in your industry, marketing and trade. (C) Identify the demographics and markets in which demand will demand the products and services, and estimate your costs when determining the cost of the goods or services such as fuel or water. [substeps] The highest demand is a production interest rate of 7 %. (D) Generally, if all other factors are equal, demand for a product will fall as its price increases. [substeps] For example, let's say that a company is about to release a new model of television.
A:
D