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
b5b4
b6a5
b6c7
b6a6
b6d6
b6c6
e6d5
e6e5
a7a5
a7a6
b7a6
b7a8
b7d5
b7c6
d7e5
d7b8
d7f6
c8c7
c8b8
d8e8
f8d6
f8e7
f8h6
f8g7
h8g8
h8h2
h8h3
h8h4
h8h5
h8h6
h8h7

## Board State Fen
2kr1b1r/pb1n1p2/1q2pP2/1ppP2B1/2p5/2N3P1/PP3PBP/R2Q1RK1 b - - 4 15
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
b5b4
b6a5
b6c7
b6a6
b6d6
b6c6
e6d5
e6e5
a7a5
a7a6
b7a6
b7a8
b7d5
b7c6
d7e5
d7b8
d7f6
c8c7
c8b8
d8e8
f8d6
f8e7
f8h6
f8g7
h8g8
h8h2
h8h3
h8h4
h8h5
h8h6
h8h7

## Board State Fen
2kr1b1r/pb1n1p2/1q2pP2/1ppP2B1/2p5/2N3P1/PP3PBP/R2Q1RK1 b - - 4 15
assistant
b5b4