Which option is correctly identified as a subdomain of example.com?

The choice that is correctly identified as a subdomain of example.com is about.example.com. A subdomain is a part of a larger domain and is used to organize or categorize information in a way that's separate from the main domain. In this case, "about" is a prefix to the main domain "example.com," establishing it as a subdomain.

When you use "about.example.com," it indicates a specific section of the main domain that can host its own content, which distinguishes it from the main website, example.com. Subdomains can serve various purposes, such as directing users to specific services or sections without needing a completely different domain name.

The other choices do not represent subdomains of example.com. For instance, example.co.uk and example.org are entirely different domains with their own overall domain spaces. They do not have a hierarchical relationship with example.com. Similarly, example.com.org is not a valid subdomain but rather suggests a combination of different domain structures that do not function under example.com. Thus, only about.example.com meets the criteria for being a subdomain of example.com.