Final answer:
Behavioral segmentation of business markets in the U.S. is generally based on the usage rate of a product or service, which indicates the intensity or frequency of use by businesses.
Step-by-step explanation:
The basis for conducting behavioral segmentation of business markets in the U.S. is most accurately represented by option c) Usage rate. This approach segments markets based on how frequently or intensively a product or service is used by businesses. Categories such as occasional use, regular use, and heavy use are common ways to differentiate within a market. While other factors like the North American Industry Classification System (NAICS) code, number of employees, and employee lifestyle do play roles in market segmentation, they are more aligned with demographic and industry-specific segmentation rather than behavioral segmentation.