What was the entrant in round 16 were Ferrari was the constructor?
CREATE TABLE "drivers_and_constructors" (
  "entrant" text,
  "constructor" text,
  "chassis" text,
  "engine" text,
  "tyre" text,
  "driver" text,
  "rounds" text
);
SELECT "entrant" FROM "drivers_and_constructors" WHERE "rounds"='16' AND "constructor"='ferrari';