The article “Is There a Market for Functional Wines? Consumer Preferences and Willingness to Pay for Resveratrol-Enriched Red Wine” (Food Quality and Preference 2008: 360–371) included the following information for a variety of Spanish wines:
a. Region of origin
b. Price of the wine, in euros
c. Style of wine (young or crianza)

d. Production method (conventional or organic)
e. Type of grapes used (regular or resveratrol-enhanced) Classify each of these variables as quantitative or categorical.