Final answer:
ICFs use expanded polystyrene (EPS) to form a concrete mold for walls.
Step-by-step explanation:
The correct answer is ICFs (Insulated Concrete Forms).
ICFs use expanded polystyrene (EPS) to form a concrete mold for walls. These forms are made of interlocking polystyrene foam panels that are filled with concrete to create a strong and energy-efficient wall system.
ICFs are a popular construction method due to their excellent insulation properties, durability, and ease of installation.