Given the available moves based on the current board state in FEN notation, think carefully about which move would be best, then make that move. Be sure to note your color indicated in the FEN notation before deciding.
## Available Moves
a5a4
a6b6
a6a8
a6a7
c6c5
e6e5
f6f5
h6h5
c7b7
c7c8
d7c5
d7e5
d7b6
d7b8
d7f8
d8e8
d8e7
d8c8

## Board State Fen
3k4/1Rrn1p2/r1p1pp1p/p7/3NP3/2P2PK1/P5PP/1R6 b - - 3 21
system
You are a chess playing AI.
user
Given the available moves based on the current board state in FEN notation, think carefully about which move would be best, then make that move. Be sure to note your color indicated in the FEN notation before deciding.
## Available Moves
a5a4
a6b6
a6a8
a6a7
c6c5
e6e5
f6f5
h6h5
c7b7
c7c8
d7c5
d7e5
d7b6
d7b8
d7f8
d8e8
d8e7
d8c8

## Board State Fen
3k4/1Rrn1p2/r1p1pp1p/p7/3NP3/2P2PK1/P5PP/1R6 b - - 3 21
assistant
c7b7