Which of the following configurations is not designed for optimal digging?

The dozer configuration is not primarily designed for optimal digging. Rather, it is specifically designed for pushing materials such as soil, rock, and debris over the ground. This configuration features a large, flat blade mounted on the front of the machine that allows the operator to move substantial amounts of earth efficiently.

While other configurations like the clamshell and scraper are specifically tailored for various digging tasks, the dozer's function is more aligned with grading and leveling rather than precise excavation. The loader configuration also focuses on carrying and moving materials, but with a bucket that allows for some digging capability. Understanding the intended purpose of each configuration clarifies why the dozer is less suited for optimal digging compared to the others mentioned.