Which HTML tag is used to define an unordered list?

The correct choice, which is the

tag, is pivotal in HTML for defining an unordered list. An unordered list is a type of list where the order of the items does not have significance, and typically, a bullet point is used to represent each item. The
tag allows web developers to group list items together in a way that visually and semantically indicates they are part of a whole without implying any sequential order.

The

, which is used for ordered lists, signifies lists where the sequence of items is important and numbers are used instead of bullet points. The tag does not exist in standard HTML, making it an invalid option. The

tag is used to create a description list, where terms and descriptions are associated but not organized in a simple list format like that provided by the unordered list. Understanding the proper use of these tags helps in correctly structuring content for clarity and accessibility.