The author mentions the creation of "blobs" of different temperatures in the Earth's outer core primarily in order to A. present a way in which the venting of heat from the outer core might disturb the heat-circulation pattern within the outer core B. provide proof for the proposal that ventilation of heat from the outer core into the mantle triggers polarity reversal C. give an example of the way in which heat circulates between the Earth's outer core and the Earth's exterior D. describe how the outer core maintains its temperature by venting its excess heat into the Earth's mantle E. argue in favor of the theory that heat circulation in the Earth's interior produces the magnetic field