Classical mechanics is not considered a sub-discipline of quantum mechanics; rather, it is the framework that describes the motion of macroscopic objects under everyday conditions. However, if we were to interpret your question in the context of their relationship, the most relevant statement would be:
Events in classical mechanics are smooth and predictable.
This statement highlights how classical mechanics operates under principles that yield predictable outcomes for macroscopic systems, while quantum mechanics deals with the inherently probabilistic and less predictable behavior of systems at the atomic and subatomic levels.