What prevents the AFT potable water tank from freezing?

The correct answer is based on the functionality of a heater blanket. Heater blankets are specifically designed to provide thermal insulation and maintain a certain temperature to prevent the contents of the tank from freezing, especially in colder conditions. When installed on the AFT potable water tank, the heater blanket generates heat and helps to keep the water temperature above freezing, making it a crucial feature for operational safety and efficiency.

While the other options present considerations regarding the tank's location and materials, they do not offer the same direct and active method for preventing freezing. For instance, while the tank being in a heated area may contribute to warmth, it is not guaranteed that the ambient temperature will always be above freezing. Similarly, being made of frost-resistant materials may offer some resilience against freezing, but they do not actively heat the water. The lack of pressurization in the AFT tail section doesn’t contribute to maintaining temperature either. Thus, the installation of a heater blanket serves as the most effective and targeted method to prevent the AFT potable water tank from freezing.