Final answer:
The builders of the Mackinac Bridge primarily used d. applied physics in its construction.
Step-by-step explanation:
The builders of the Mackinac Bridge primarily used d. applied physics in its construction. Physics is the foundation of many important disciplines and contributes directly to engineering, architecture, and geology, among others.
In the case of the Mackinac Bridge, physics played a crucial role in ensuring the structural stability, analyzing earthquake risks, and understanding heat transfer in the Earth.