HBH Basic Web 1: Source Clue

I just found out about Hellbound Hackers, an eductational hacking website which is supposed to legally simulate a realistic hacking environment, just like Hack This Site. The first challenge is, as expected, very simple. Just take a look at the source code. In the source to my challenge, I found an HTML comment that looked like this:

<!-- it has four legs and most of the time its called 'man's best friend'-->

Apparently, this mission exists just to check whether the user is capable of viewing the source code. It’s probably a riddle in order to prohibit social freaks that never talk to people from further endangering their species.

Of course, the answer and password was “dog”