How many shifts were involved in building sets leading up to the production of Star Wars?

The correct choice highlights that the building of sets for the production of Star Wars involved three shifts. This was necessary due to the complexity and scale of the film's production, which required extensive and intricate sets to realistically portray the various alien landscapes and environments.

Utilizing multiple shifts meant that work could be done around the clock, allowing for faster completion of set construction. This method is typical in large-scale film productions where time is of the essence and the demands of the filming schedule can be intense. The efficient use of labor with three shifts showcases the commitment to detail and the urgency of the project, ensuring that everything was in place before shooting began.

By contrast, fewer shifts would generally indicate a less complex project or one that perhaps had a more relaxed timeline, which isn’t the case for such a landmark film as Star Wars. Thus, the choice of three shifts correctly reflects the high level of preparation and effort involved in the film's production.