Tell me the School/Club team of the player from the United States that play'de guard?
CREATE TABLE "r" (
  "player" text,
  "nationality" text,
  "position" text,
  "years_for_jazz" text,
  "school_club_team" text
);
SELECT "school_club_team" FROM "r" WHERE "nationality"='united states' AND "position"='guard';