HTML5 Fundementals - Question 1/10

We hear that the internet is based on HTML. What is HTML exactly?

HTML is a protocol that is used to route data across the internet, via TCP/IP.
HTML is a text-based language that is used to structure and present content on the world wide web.
HTML is a binary file format that codes web pages for use on the Internet.
HTML is a disk file system used in modern operating systems.