Final answer:
Type II fluid is a thickened freezing point depressant that offers a longer holdover time for de-icing and anti-icing on aircraft surfaces.
Step-by-step explanation:
The type of de-icing and anti-icing fluid that is a thickened freezing point depressant fluid, which provides a longer holdover time, is Type II. These specialized fluids are used on aircraft surfaces to prevent ice formation and to remove existing ice. Freezing point depression is a property of solutions that is used to prevent and remove ice, not just in aviation, but also in other applications such as roadway de-icing with salts and as antifreeze in automobile radiators. Covalent compounds like ethylene or propylene glycol are used in these applications because they not only lower the freezing point of liquids, but also increase the boiling point, making them useful throughout the year.