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
b3b4
d3e2
d3d2
d3c3
d3c2
e3e4
g3g4
h3h4
d4c2
d4c6
d4e2
d4e6
d4b5
d4f3
d4f5

## Board State Fen
8/8/1p2pp2/p1bk1p1p/P2N1P2/1P1KP1PP/8/8 w - - 4 39
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
b3b4
d3e2
d3d2
d3c3
d3c2
e3e4
g3g4
h3h4
d4c2
d4c6
d4e2
d4e6
d4b5
d4f3
d4f5

## Board State Fen
8/8/1p2pp2/p1bk1p1p/P2N1P2/1P1KP1PP/8/8 w - - 4 39
assistant
d4b5