Do I even know myself at all?

I just tried to retrieve my NYT's online account. Of course I don't remember my user name or password - I never do. But what really stumped me was I had no idea of the answer to my secret question - which is "What is your favorite book?" I was so interested to find out what is my favorite book that I stumbled around the NYT online account interface until I found the question/answer section... only to find that my answer is not visible other than six little black circles.

So, with that clue, six letters no spaces, can any one tell me, what is my favorite book?
And more importantly, how can I not know this?