A field that is Null is empty and has no value

The W3C is an organization that:

a) maintains and runs the internet. b) removes junk and broken links from the web. c) developed e-mail. d) helps to develop web technologies.

In the figure above, if the first image is the original, the number 3 is a sample of the effects of the ____________________ tool.

Fill in the blank(s) with the appropriate word(s).