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
b1a1
b1d1
b1c1
b1b8
b1b7
b1b6
b1b5
b1b4
b1b3
b1b2
e1c1
e1d1
e1f1
e1e3
e1e2
g1h2
g1h1
g1f1
c2a4
c2b3
c2d1
c2d3
d2c1
d2h6
d2g5
d2f4
d2e3
d2d1
d2e2
d2d3
g2g4
g2g3
a3c1
a3b2
a3d6
a3c5
a3b4
f3e5
f3g5
f3h2
f3h4
h3h4
d4e5
d4d5

## Board State Fen
1r2rbk1/2qb1ppp/p2p1n2/4p3/2pPP3/B1P2N1P/P1BQ1PP1/1R2R1K1 w - - 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
b1a1
b1d1
b1c1
b1b8
b1b7
b1b6
b1b5
b1b4
b1b3
b1b2
e1c1
e1d1
e1f1
e1e3
e1e2
g1h2
g1h1
g1f1
c2a4
c2b3
c2d1
c2d3
d2c1
d2h6
d2g5
d2f4
d2e3
d2d1
d2e2
d2d3
g2g4
g2g3
a3c1
a3b2
a3d6
a3c5
a3b4
f3e5
f3g5
f3h2
f3h4
h3h4
d4e5
d4d5

## Board State Fen
1r2rbk1/2qb1ppp/p2p1n2/4p3/2pPP3/B1P2N1P/P1BQ1PP1/1R2R1K1 w - - 2 21
assistant
b1d1