Final answer:
The material of choice for the driveshaft tube in heavy trucks due to its strength is steel.
Step-by-step explanation:
The material of choice for the driveshaft tube in the heavy-truck market because of its strength is steel.
Steel alloys are known for their strength and durability, making them ideal for applications where high strength is required, such as heavy trucks.
While other materials like fiberglass, brass, and aluminum are used in various industries, steel stands out as the preferred material for driveshaft tubes in the heavy-truck market due to its superior strength.