Which HTML tag is used to define an unordered list?

The tag used to define an unordered list is

. This tag creates a list in which each item is typically marked with a bullet point rather than a number, which is characteristic of ordered lists (defined by
). The
tag allows for the grouping of related items in a way that emphasizes their equal importance rather than a sequential order.

Additionally, within the

tag, individual list items are defined using the
• tag. This structure is key for creating lists in HTML as it helps in organizing content in a clear and accessible manner for both users and search engines. The other choices do not represent correct HTML specifications for unordered lists. For instance,
  is specifically used for ordered lists, is not a recognized HTML tag, and also is not a valid HTML element for list creation. Therefore,
  is the appropriate tag for creating unordered lists.