My pick for A

Lloyd Alexander pops first in to my head for a fantasy author for A. As for which book, the obvious choice might be "The book of Three" (first in the Chronicles of Prydain) or Westmark (first in the Westmark trilogy), but I have recently reread these (I highly recommend both if you haven't) and thought this challenge presented me with an opportunity to explore new reads. I will confess to living in a small town with a small library, so I was limited in choice once I nixed all the Alexander books I had read, but a few remained and The Arkadians struck me as interesting.

So my A book for January is The Arkadians by Lloyd Alexander.