?Read the following extract from an article about market targeting, and the questions followed. ?For each question 15--20, mark one letter (A, B, C, or D) on your Answer Sheet for the answer you choose. The company might decide to ignore market segment differences and go for the whole market with one market offer. This approach focuses on what is common in the needs of consumers rather than on what is difficult. Product and marketing programs are designed to appeal to most buyers. Mass distribution and mass advertising are relied on. An example of undifferentiated marketing would be the launch of a new chocolate bar targeted at everyone. This approach provides cost economics. Production, inventory and transportation costs are kept low by the single product line. Similarly, advertising, market research and product management costs are kept low. However, most modern marketers have strong doubts about this strategy. It is very difficult to develop a product or brand that will satisfy all customers. Heavy competition will usually be attracted and therefore margins will often be low. A company may decide to target several market segments and design separate offers for each. General Motors tries to produce a car for every 'purse, purpose and personality'. By establishing a strong position in several segments, consumers’ overall identification with the company will be strengthened and therefore provide a better chance of repeat purchasing. Differentiated marketing typically creates more total sales than undifferentiated marketing. But the production and marketing costs are increased. In some cases, 'over segmentation' can Occur and a company may try to broaden its base. For example, the target market for Johnson ' & Johnsen’s baby shampoo was broadened to include adults. Many countries see a third possibility that is especially appealing when company resources are limited. Instead of going for a small share of a large market, the firm goes for a large share of a submarket. Many examples of concentrated marketing can be found. In computers Sinclair targeted the bottom end of the home computer market； in cars, Saab focuses on the luxury sports car market in clothes, Laura Ashley originally targeted a distinct segment of the women’s clothes market. Through this approach, a strong market position can be achieved, operating costs can be kept low and, if targeted well, the firm can earn a high rate of return on its investment. At the same time, higher than normal risks are involved. The particular market segment can tarn sour； larger competitors may well enter the same segment with many more marketing resources. For these reasons, many companies prefer to diversify in several segments. In terms of application, many factors must be considered when choosing one of the above strategies. When a firm's resources are limited, concentrated marketing make the most sense. Undifferentiated marketing is more suited when the product is homogeneous like grapefruit or steel. The product's stage in its life cycle must also be considered. When a new product is introduced, it is often practical to launch just one version and in that case undifferentiated or concentrated marketing makes the most sense. Differentiated marketing is more applicable to more mature products. Finally, competitors~ marketing strategies are important. According to the first paragraph, what the main advantage does undifferentiated marketing have?