What does the term "lift lines" refer to in rigging?

The term "lift lines" specifically refers to the lines that connect to the load and facilitate the lifting motion through rigging systems. These lines play a critical role in a rigging setup as they are responsible for carrying the weight of the load while allowing it to be hoisted, lowered, or moved.

In rigging systems, lift lines are integral to the operational mechanics, as they transmit the forces generated by the lifting mechanism, such as a winch or a hoist, directly to the load. A clear understanding of lift lines is essential for riggers to calculate load capacities and ensure safe lifting practices, contributing to the overall reliability and safety of rigging operations.

While the other options involve important components of rigging, they do not accurately define what lift lines are. For instance, securing loads is typically associated with securing lines or chokers, while safety lines and backup lines serve different purposes focused on safety and contingency, rather than the lifting function itself.