CREATE TABLE table_13278 ("School" TEXT, "Location" TEXT, "Mascot" TEXT, "IHSAA Class" TEXT, "County" TEXT, "Year Joined" TEXT, "Year Left" TEXT, "Conference Joined" TEXT)

Which IHSAA class A school are the Cavaliers from?
SELECT "County" FROM table_13278 WHERE "IHSAA Class" = 'a' AND "Mascot" = 'cavaliers'
SELECT "County" FROM "table_13278" WHERE "IHSAA Class" = 'a' AND "Mascot" = 'cavaliers'