CREATE TABLE table_43817 ("Res." TEXT, "Record" TEXT, "Opponent" TEXT, "Method" TEXT, "Event" TEXT, "Round" TEXT)

What event was the opponent Karl Knothe and had a submission (rear naked choke)?
SELECT "Event" FROM table_43817 WHERE "Method" = 'submission (rear naked choke)' AND "Opponent" = 'karl knothe'
SELECT "Event" FROM "table_43817" WHERE "Method" = 'submission (rear naked choke)' AND "Opponent" = 'karl knothe'