Why should links be tested regularly?

to keep them reliable
to maintain variety on the website
to see how it looks on your monitor
to see if they are used

All of the options provided are valid reasons to test links regularly. However, the most important reason is to ensure that the links are reliable and functioning correctly. Regular testing ensures that the links are not broken or leading to error pages, which may result in a negative user experience. Additionally, testing links helps to detect any potential issues with URL redirection or incorrect linking.