What is a digger derrick primarily used for?

A digger derrick is primarily used for digging holes, setting poles, and lifting heavy objects, which makes it a versatile piece of equipment in applications such as electrical utility work and construction. The primary function of a digger derrick is to excavate a hole for the installation of utility poles and other structures while also providing the lifting capacity required to set these poles into place. Its design incorporates both a digging mechanism and a boom with a winch that allows it to maneuver heavy materials safely and effectively.

While drilling wells and setting foundations do involve excavation work, they typically require different types of specialized equipment better suited for those particular tasks. Similarly, while transporting heavy machinery is important in construction and utility operations, it usually involves flatbed trucks or cranes rather than digger derricks, which are specifically designed to facilitate digging and lifting. Therefore, option C accurately encapsulates the primary capabilities of the digger derrick.