APA, and ISBN aren't internet-related, so they're clearly not the answer. DOI is internet-related in a way, but still doesn't have anything to do with addresses.
An URL stands for uniform resource locator, which we all call internet address or web address. What it does is that it locates web-pages in a computer network using a code (URL).
Answer:
[tex]\boxed{\bf~C.~URL}[/tex]
Hope it helped,
BioTeacher101
