Answer:
<!--Jose,10/09/2019. This code validates to HTML5-->
Step-by-step explanation:
HTML(Hyper Text Markup Language) is used to write content of the web page.It uses different HTML elements to do that.
HTML comments are to define,describe or to provide extra information the elements in the HTML code .Anything written inside the HTML comment is not shown on the web page.It is only present in the code.
HTML comment is written as <!-- comment -->.Anything written inside <!-- --> is considered as comment in HTML.
So the line written above in the answer can be inserted so that other developers can know that this page was created by Jose and it is of HTML5.