Which type of expressions can be removed through the Expression dialog box?

The option identifying expressions that are not used as the correct answer highlights the functionality of the Expression dialog box in Siemens NX. This dialog is specifically designed to manage expressions within a modeling environment, allowing users to streamline their models by removing any defined expressions that are no longer referenced or utilized in the design.

Unused expressions can clutter the model, leading to confusion or potential errors in future updates or modifications. By allowing users to remove these unused expressions, Siemens NX helps maintain a clean and efficient workflow, ensuring that only relevant parameters are active and manageable within the design.

In contrast, while feature expressions may be critical for defining specific model attributes, removing them could disrupt the integrity of the associated features. Locked expressions cannot be altered or deleted through the dialog, as they are secured against changes to maintain design stability. Lastly, the ability to remove any expression is not accurate since certain expressions serve essential roles in the modeling process. This targeted capability of the Expression dialog box to remove only the unused expressions underscores the importance of organization and clarity within the modeling environment.