Surveys consistently show that the best-selling ice cream flavor is vanilla, although those who prefer chocolate rarely order vanilla. Vanilla-flavored candy, then, probably sells better than chocolate-flavored candy. Which of the following is an assumption upon which the author of the argument relies? ['Preferences for certain ice cream flavors are similar to preferences for candy flavors.', 'Because someone prefers vanilla ice cream does not mean he prefers vanilla-flavored candy.', 'Someone who prefers vanilla ice cream may still order chocolate on occasion.', 'Those who prefer neither vanilla nor chocolate ice cream also prefer other flavors of candy.']