Final answer:
The lakes found in the north polar region of Titan are indeed filled with liquid, specifically a mixture of hydrocarbons such as methane and ethane; this has been confirmed by data and images from the Cassini-Huygens mission.
Step-by-step explanation:
The statement that lakes found in the north polar region of Titan are filled with liquid is true. Titan, Saturn's fascinating moon, is characterized by its dense nitrogen atmosphere with a considerable amount of methane. The Cassini-Huygens mission provided imagery that gives clear evidence of large methane lakes near Titan's polar regions. These lakes, as well as streams and rivers, are comprised of liquid hydrocarbons, mainly a mixture of methane and ethane, rather than water. Titan exhibits a full cycle analogous to Earth's hydrological cycle, but with these hydrocarbons, including evaporation, cloud formation, and precipitation as hydrocarbon rain that feeds into its lake and river systems.