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
c4b2
c4b6
c4d2
c4d6
c4a3
c4e3
c4e5
e8a8
e8b8
e8c8
e8d8
e8e5
e8e6
e8e7
e8h8
e8g8
e8f8
d7e7
d7d8
d7c8
d7c7
c6c5
d5d4
f7f6
b5a4
b5b4

## Board State Fen
4r3/3k1p2/2p5/pp1pPPp1/P1n3P1/2P3B1/2P3K1/1R6 b - - 1 40
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
c4b2
c4b6
c4d2
c4d6
c4a3
c4e3
c4e5
e8a8
e8b8
e8c8
e8d8
e8e5
e8e6
e8e7
e8h8
e8g8
e8f8
d7e7
d7d8
d7c8
d7c7
c6c5
d5d4
f7f6
b5a4
b5b4

## Board State Fen
4r3/3k1p2/2p5/pp1pPPp1/P1n3P1/2P3B1/2P3K1/1R6 b - - 1 40
assistant
b5a4