The fourth industrial revolution $($Industry $4\mathrm{.}0)$ is

A$.$ the interconnectivity of objects, embedded with software, sensors$,$ and actuators that enable these objects to collect and exchange data over a network without requiring human intervention.

B$.$ the ongoing automation of traditional manufacturing and industrial practices, using modern smart technology.

C$.$ a constellation of technologies, from machine learning to natural language processing, that allows machines to sense, comprehend, act, and learn.

D$.$ the use of computerized systems in manufacturing to track and document the transformation of raw materials into finished goods and optimize their production output.