Final answer:
The best description of a target market based on customer behavior is people who want to make a purchase immediately, which is a direct indicator of their consumer behavior as opposed to demographic factors.
Step-by-step explanation:
The best description of a target market based on customer behavior is people who want to make a purchase immediately (option C). This choice highlights the behavioral aspect by identifying customers' intent to act (i.e., to make a purchase), which is a direct indicator of their consumer behavior. In contrast, the other options describe target markets based on demographic factors and not on behavior. Marital status and family size (option A), educational attainment (option B), and preparation for seasonal changes (option D) characterize markets based on demographics rather than behavior.