Janus Corporation uses a tool that embeds a code into all of its digital documents. It then scours the internet, searching for codes that it has embedded into its files. When Janus finds an embedded code on the internet, it knows that confidential information has been leaked. Janus then begins identifying how the information was leaked and who was involved with the leak. Janus is using

a$.$

a digital watermark.

b$.$

a spybot.

c$.$

a keylogger.

d$.$

data loss prevention software.