What results of the Cassini radar mapping of Titan have provided the strongest evidence so far for liquid bodies on its surface?
A) Mapping of multiple mountain ranges and canyon systems across Titan's surface.
B) Mapping of a large number of likely river networks across Titan's surface.
C) Tracking of multiple large "waves" as they moved across the surface of a likely lake or ocean.
D) Identification of multiple large, smooth regions near Titan's poles, which could be lakes or oceans.
E) Detection of changes in the heights of multiple likely lakes or oceans due to tidal effects.