PokerStars No-Limit Hold'em, $1.00 BB (5 handed) Hand History Converter Tool from FlopTurnRiver.com (Format: FlopTurnRiver)

Button ($151.95)
SB ($223.40)
Hero ($146)
UTG ($55.25)
MP ($269.30)

Preflop: Hero is BB with 7, 8.
2 folds, Button raises to $3, 1 fold, Hero calls $2.

Flop: ($6.50) 9, 4, A (2 players)
Hero checks, Button bets $4, Hero raises to $12, Button calls $8.

Turn: ($30.50) Q (2 players)
Hero bets ???