Check to see what links are on the user's web page and make sure they work; if a link is broken, they identify it and include this information as part of the data about that page.

a. backdoors

b. subscribers

c. clients

d. crawlers

d. crawlers

Explanation:

Crawlers or spider web

It is an automated software that systematically inspects and tracks all Internet pages to index and position them in the search engine.

The Web Spider starts with a few initial URL’s, called web seed and goes discovering the web pages linked to our website and tracking them.

Collect and add URLs to the list to process and index them later.

The Cwarler uses the robots.txt file and the meta tag to collect the information that the owner of the Web has left, such as pages he wants me to ignore, non-index pages.

Track content and hyperlinks. With this information, create a structure of your website with all the web pages that exist.

true never assume something it makes an a** out of u and me.