Answer:
d. CSS can be included in an HTML document
Explanation:
HTML (Hypertext Markup Language) and CSS (Cascading Style Sheets) are not <em>programming languages</em>. They are, in fact, a different kind of <em>computer languages</em> and are some of the essential tools used in common web pages nowadays.
HTML and HTML5 are <em>different</em>. The latter is a new version of HTML which implies some improvements such as the availability of other technologies and features not found in HTML.
HTML is a <em>markup language</em>, i. e., a kind of computer language like <em>TeX</em>, <em>LaTeX</em>, <em>troff</em>, among others, that defines the <em>structure</em> of a text, and it tells to a computer how to show it in a web page using tags embedded into the content of the document. For example, a paragraph is defined using a tag like this <p> text inside </p>, a title: <title> text inside </title>, and so on with images, tables, et cetera.
CSS is a <em>style sheet language, </em>that is<em>,</em> another kind of <em>computer language</em> whose main emphasis is the <em>appearance</em> of the web page, telling the computer the <em>presentation </em>the <em>structured document</em> is about to have, that is, <em>how the document should look</em>.
As a result, CSS is used to describe the presentation of documents written in HTML and <em>can be included</em> in it.
On the other side, <em>programming languages</em> are <em>formal languages </em>(like the ones of mathematics and logic), that is, with some rules and a particular syntax intended to "communicate instructions to a machine, particularly a computer" [Wikipedia, 2019], and some examples of high-level programming languages are those like C, Python, Fortran, Lisp, CommonLisp, Pascal, JavaScript, among many others.
