Final answer:
The correct term for URLs that no longer work is 'Dead links'. These are problematic for user experience and SEO, and should be fixed by webmasters to maintain site quality.
Step-by-step explanation:
Robot programs on the internet often check for URLs that no longer work. These non-functional links are commonly referred to as Dead links or broken links. In this context, the correct answer to the question is B) Dead links. When a URL does not lead to a functioning web page, usually due to the page being moved or deleted, it is called a dead link. This can negatively affect both user experience and SEO rankings for a website, which is why it's important for webmasters to regularly use tools to scan their websites for such issues and promptly address them.