Which innovation is Jean-Antoine Lepine known for in watch design?

Jean-Antoine Lepine is recognized for his significant contributions to watch design, particularly through the development of the single plate and bridge calibre. This innovation streamlined the movement of watches by utilizing a single plate to support the gear train, which reduced the number of components needed and simplified the overall design. The bridge system also allowed for easier assembly and repair of the timepieces, significantly influencing the manufacturing processes and contributing to the efficiency of watchmaking at the time. Lepine's designs laid the groundwork for many modern movements, making his work a cornerstone in the evolution of horology.

The other options refer to different innovations or developments within the field of watchmaking, but they are not attributed to Lepine. The marine chronometer was developed earlier and is associated with other inventors, while quartz technology and automatic mechanisms emerged much later in the history of horology.