What must be extended before adjusting counterweights on a carrier-mounted crane?

Before adjusting counterweights on a carrier-mounted crane, it is essential to extend the outrigger beams and jacks. This action provides stability to the crane, ensuring that it is properly supported on all sides before any modifications, such as adjusting counterweights, are made.

Outriggers are crucial for maintaining the crane's center of gravity and stability, especially when working with heavy loads. Extending the outrigger beams increases the footprint of the crane, distributing the weight more evenly and preventing tipping or instability. The jacks serve to further stabilize the crane against vertical loads. This safety practice is vital, as failure to properly extend the outriggers before making adjustments can lead to accidents or equipment failure.

In contrast, the other options do not pertain directly to the initial steps required for safely adjusting the crane's counterweights. Extending the boom and hoist, for instance, relates to lifting and positioning loads rather than stabilizing the crane itself. Similarly, the crane’s stabilizers and lift cables serve different functions that do not address the immediate requirement of ensuring stability during counterweight adjustments.