A metal door constructed of heavy corrugated steel typically uses what material for its interior core?

A heavy corrugated steel door typically incorporates a core made from metal. This choice is crucial for providing additional strength and durability to the door, aligning with its overall purpose as a security feature. The metal core enhances the door's resistance to impact and penetration, making it more effective in situations that may involve forceful entry.

Other options like glass, wood, or Styrofoam do not provide the level of strength and security that a corrugated steel door aims to deliver. Glass would be inappropriate due to its fragility, while wood, although sometimes used in some types of doors, is not suitable for heavy-duty applications where metal would provide superior performance. Styrofoam, primarily used for insulation, lacks the rigidity and protective qualities necessary for a durable steel door. Therefore, metal stands out as the most appropriate material for the core of a heavy corrugated steel door.