84. Which statement best captures the gist of the passage? (A) Undersea brine pools are beautiful but ultimately insignificant features of the ocean floor. (B) Undersea brine pools are the main source of methane used in energy production. (C) Undersea brine pools demonstrate the extreme conditions under which life can exist in spite of challenges. (D) Undersea brine pools are hazardous zones that should be permanently sealed off.