Final answer:
Proprietary tags are C) tags that work only on certain browsers. They are specially created and used by a specific browser or software and may not be recognized by other browsers or software. Hence, C) is correct.
Step-by-step explanation:
Proprietary tags are tags that work only on certain browsers. These tags are specially created and used by a specific browser or software and may not be recognized by other browsers or software.
They are typically used to add specific functionalities or styles that are specific to a particular browser or software.