What is one key aspect of parliamentary procedure according to the basic principles?

One key aspect of parliamentary procedure is the principle that only one item of business can be discussed at a time. This ensures that discussions remain focused and organized, allowing members to deliberate effectively and make decisions without confusion. By addressing each piece of business sequentially, parliamentary procedure helps to maintain order during meetings and enables participants to provide their input clearly and without interruption.

The other options, while they may pertain to different aspects of meetings, do not align with the fundamental principles of parliamentary procedure in the same way. Unanimous consent is not always required for decisions; in fact, many decisions can be made by majority vote. The expectation that all members must remain silent contradicts the idea of open discussion, where members are encouraged to share their viewpoints. Lastly, voting by secret ballot is a specific method that is not universally required, as many organizations use open voting for transparency.