If a user clicks a link to view a document on a web page and nothing happens, the most likely cause is that scripting is disabled. Many web pages use JavaScript or other scripting languages to execute functions such as opening documents, redirecting to other pages, or displaying dynamic content. If scripting is turned off in the browser's settings, these actions will not work.
B . The security settings are too high could block certain actions, but scripting being disabled is a more common cause.
C . Pop-up blockers could prevent new windows from opening, but typically wouldn't affect document viewing.
D . An invalid web certificate would prevent access to the entire site, not just a specific action like opening a document.
Reference:
CompTIA A+ Certification Exam Guide
Web Browser Security and Settings Best Practices