BB bets 3bb (donk)

Heads-up Flop | BTN vs BB | 100bb effective | Difficulty: Beginner

Hero hand

9♣9♠

Board

K♥J♦4♣

Action so far:
Preflop: Hero BTN raises 2.5bb, BB calls
Flop K♥J♦4♣
BB bets 3bb (donk)

Pot: 6bb   To call: 3bb

Villain range: KQs-K9s,KQo-KTo,QJs,JTs,J9s,QJo,JTo

Your move: