Coming after a long time and started with this question
how come -1 and -10 didn't span the whole number line !!! I got caught in the first option; I see a reason - it did not show the author name.
I guess I should have used the other half of the brain to solve this one.
Thanks for the question Hugo. I have been thinking on creating questions on Isolation levels, well I guess nothing beats this one; partly though, it solves the purpose.
Wondering what I would do next , when I am done with this one