Franco is developing a marketing segmentation plan for his designer eyeglass company. His eyeglasses are pricey compared to the competition, so Franco wants to appeal to a high$-$income marketing segment. He plans to use census data to identify his potential customers. When Franco prepares his marketing segmentation plan, he must make sure that

a$.$ the segments are small

b$.$ the advertising is bi$-$lingual

c the promotion describes product distinctions

$d$ the segments are well$-$defined