To ensure that an html document renders well in many different web browsers, it is important to include which of the following at the top of the file. a. an tag b. a doctype declaration c. a tag d. a tag

Every HTML page includes tags. A tag is a keyword surrounded by angled brackets. Most tags come in pairs; one tag is called the opening or start tag, and the other is the closing or end tag. A tag pair is case sensitive—a closing tag must have the same case as the opening tag. A closing tag is identical to an opening tag except the closing tag includes a slash before the keyword.
Tags surround content and give it definition. For example, this markup creates a first-level heading:
Pet Care 101