What are the four lengths of fast rope available?

The answer choice indicating the lengths of fast rope as 30, 60, 90, and 120 feet is correct because these specific measurements align with standard industry practices and specifications related to the deployment of fast ropes in various operational scenarios. These lengths provide a versatile range for users, ensuring they have options suited for different heights and mission requirements when descending from helicopters or other elevated platforms.

The chosen lengths are practical for tactical operations, as they accommodate both personnel and equipment needs during descent. Shorter lengths allow for more rapid descents in certain situations, while longer lengths provide increased versatility for accessing higher elevations. The specific measurements tend to be preferred in military and emergency services settings, where rapid insertion and extraction are critical.

Other choices present different sets of lengths, which may not align as closely with established standards for fast ropes used in the field.