Which Prominence (m) has a Peak of nakanai mountains high point, and an Elevation (m) smaller than 2,316?
CREATE TABLE "the_31_s_ultra_prominent_summit_of_papua" (
  "rank" real,
  "peak" text,
  "country" text,
  "island" text,
  "elevation_m" real,
  "prominence_m" real,
  "col_m" real
);
SELECT AVG("prominence_m") FROM "the_31_s_ultra_prominent_summit_of_papua" WHERE "peak"='nakanai mountains high point' AND "elevation_m"<'2,316';