Final answer:
The part of a URL given in the options is the domain (or host). 'Editor' is not part of a URL but relates to web content editing, and 'HTML' is the language for creating web pages, not a URL component.
Step-by-step explanation:
The part of a URL (Uniform Resource Locator) that is included in the options given is A. domain (or host). A URL is the address of a web page and typically includes the protocol, domain, and path to a specific page or resource on a web server.
The domain or host is the human-readable address that indicates where a resource is hosted on the internet. Option B, 'editor', is not part of a URL but is related to the person who edits content for a website. Option C, 'HTML', stands for Hypertext Markup Language, which is the standard language for creating web pages, not a part of a URL.