In which sentence is the underlined clause an adverb clause?
a) a multitude of animals, whose names may be familiar to you, also survive in the arctic region.
b.) the ship, which was a nuclear submarine, became the first vessel to pass beneath the north pole.
c.) the territory's emblematic stone, blue lazulite, looks bluer than the sky does on a clear summer day.
d.) spring brings a resurgence of life to the arctic, which is home to more than 400 species of plants.