CREATE TABLE table_31668 ("Year" TEXT, "Competition" TEXT, "Opponent" TEXT, "Score" TEXT, "Venue" TEXT)

At the VFL Reserves, who was the opponent when the score was 18.6 (114) - 21.14 (140)?
SELECT "Opponent" FROM table_31668 WHERE "Competition" = 'vfl reserves' AND "Score" = '18.6 (114) - 21.14 (140)'
SELECT "Opponent" FROM "table_31668" WHERE "Competition" = 'vfl reserves' AND "Score" = '18.6 (114) - 21.14 (140)'