Final answer:
The term global economy is the correct answer since it refers to the interconnected and competitive nature of the world markets, which allows consumers access to a plethora of choices.
Step-by-step explanation:
The expansion of competitive boundaries that allows customers many choices is represented by the concept of a global economy. This term refers to the interconnected nature of modern markets, where trade and competition are not limited by national borders, enabling consumers to access a wide range of products and services from different countries. Hence, the correct answer is b) Global economy. In contrast, a monopoly (a) is a market structure where a single firm controls the entire market, limiting consumer choice. Perfect competition (c) refers to a market with many sellers offering identical products, which is different from a scenario where differentiated products are available. Lastly, market segmentation (d) is the practice of dividing a broad consumer market into subgroups with common characteristics, which does not necessarily imply an expansion of competitive boundaries.