The ________ is a series of weights, pipes and ropes used to hang and fly scenery, curtains, and electrics in and out of sight of the audience.

The correct answer is the counterweight system, which is an essential component in theatrical rigging. This system utilizes a series of weights, ropes, and pulleys to balance the weight of the scenery, curtains, or lighting fixtures being flown in and out. The counterweights allow for a smooth and controlled movement, making it safer and easier for operators to manipulate heavy flown elements without risking injury or damaging the equipment.

In theatrical venues, the ability to efficiently raise and lower these elements is crucial for scene changes and overall production fluidity. The use of counterweights helps maintain equilibrium, ensuring that the flown items can be moved swiftly and with precision. This is important not only for the technical aspect of stage management but also for maintaining the visual aesthetics of a production, as it allows for seamless transitions and enhanced storytelling.

Other terms like "drop" refer to a specific type of fabric used in a production, while "alcove" generally pertains to a recess in a wall, which does not relate to rigging. A "batten" is a horizontal pipe used for hanging elements, but it does not encompass the entire system of weights and ropes. Hence, the counterweight system is the most comprehensive and accurate term to define this rigging mechanism.