Final answer:
The Reach Toothbrush available in different bristle types and for different age groups represents a single product with multiple market segments, showcasing product differentiation and monopolistic competition.
Step-by-step explanation:
Among the given examples, an example of a single product with multiple market segments is b) Reach Toothbrush is available in a soft, medium, and hard bristle for adults and kids. This illustrates how a company can create variations of a single product (toothbrushes) to cater to different preferences and needs (soft, medium, hard bristles) and for different demographic groups (adults and kids). It's a demonstration of product differentiation within monopolistic competition, where a variety of similar but not identical products are offered by numerous firms, giving each a mini-monopoly on its specific offering and maintaining competitive conditions.