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
c6c5
e6e5
h6h5
d7c8
d7e8
f7f5
f7f6
g7g5
g7g6
a8a6
a8a7
a8c8
a8b8
d8e8
d8e7
d8c8

## Board State Fen
r2k4/1R1b1pp1/2p1p2p/p7/5P1P/2PB4/P4PP1/5K2 b - - 2 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
c6c5
e6e5
h6h5
d7c8
d7e8
f7f5
f7f6
g7g5
g7g6
a8a6
a8a7
a8c8
a8b8
d8e8
d8e7
d8c8

## Board State Fen
r2k4/1R1b1pp1/2p1p2p/p7/5P1P/2PB4/P4PP1/5K2 b - - 2 21
assistant
d8c8