The correct answer is (a) Polycarbonates.
Polycarbonates are a type of thermoplastic polymer that is known for its strength, toughness, and transparency. They are often used in applications where high impact resistance is required, such as in bullet-proof windows.
Polyurethanes are a type of elastomer that is known for its flexibility and resilience. They are often used in applications where cushioning or vibration damping is required, such as in car seats or mattresses.
Polystyrene is a type of thermoplastic polymer that is known for its low cost and ease of processing. It is often used in applications where low cost and mass production are important, such as in disposable packaging or insulation.
Polyamides are a type of thermoplastic polymer that is known for its strength and toughness. They are often used in applications where high performance is required, such as in gears or bearings.
In conclusion, polycarbonates are the best choice for making bullet-proof windows because they are strong, tough, and transparent.