The correct answer is C: icebergs contain many more molecules than pots of water.
While boiling water is at a higher temperature (100°C at sea level), the total thermal energy in an iceberg can be greater because it is much larger in volume, containing significantly more water molecules. Thermal energy depends not only on temperature but also on the number of molecules present. An iceberg can hold a vast amount of thermal energy despite being at a lower temperature than boiling water.
The other options do not correctly explain the relationship between heat in icebergs and boiling water.