I was going for a c/r but I'm not sure if that's my best extraction line, given the action?

Full Tilt No-Limit Hold'em, $2 BB (8 handed) Full Tilt Converter Tool from FlopTurnRiver.com (Format: FlopTurnRiver)

Hero ($205.90)
BB ($195)
UTG ($194.15)
UTG+1 ($91.25)
MP1 ($312.55)
MP2 ($76.70)
CO ($206.50)
Button ($69.25)

Preflop: Hero is SB with 9, 9.
UTG raises to $6, 2 folds, MP2 calls $6, CO calls $6, 1 fold, Hero calls $5, BB calls $4.

Flop: ($30) 7, 9, K (5 players)
Hero checks, BB checks, UTG bets $30, MP2 folds, CO calls $30, Hero ????