What materials must be used to build the boats for the Armada Boat Race?

The correct answer specifies that boats for the Armada Boat Race must be constructed using cardboard and duct tape. This choice is appropriate because these materials are both lightweight and easily accessible, which is essential for a race where speed and buoyancy are crucial. Cardboard provides a good balance of structural integrity while still being lightweight enough to allow for more competitive speeds when on the water. Additionally, duct tape is an effective adhesive that is not only strong but also waterproof, which is vital for ensuring the boat remains intact in wet conditions and can stay afloat during the race.

In contrast, the other materials proposed are either too heavy or not conducive to the race's requirements. Wood and nails may result in sturdiness, but the overall weight would likely hinder performance. Similarly, plastic and adhesive could work for certain designs, but they may not provide the same level of ease in construction and weight management as cardboard and duct tape. Metal and screws, while durable, would certainly add unwanted weight, making it difficult for the boats to compete effectively. Therefore, cardboard and duct tape are ideal for creating efficient and competitive race boats.