Beware of taking a wrong turn

[Siegmund]

MP1 is new. CO is loose passive; she will limp with any suited connector in any seat; if she sees the flop she will call to see the turn and river; if she raises she has the nuts or close to it.

Absolute Poker 1/2 Hold'em (9 handed) converter

Preflop: Hero is BB with 7[img]/images/graemlins/spade.gif[/img], 9[img]/images/graemlins/club.gif[/img].
<font color="#666666">2 folds</font>, MP1 calls, <font color="#666666">2 folds</font>, CO calls, <font color="#666666">2 folds</font>, Hero checks.

Flop: (3.50 SB) 7[img]/images/graemlins/club.gif[/img], 6[img]/images/graemlins/spade.gif[/img], K[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(3 players)</font>
Hero checks, MP1 checks, CO checks.

Turn: (1.75 BB) 8[img]/images/graemlins/spade.gif[/img] <font color="#0000FF">(3 players)</font>
Hero checks, <font color="#CC3333">MP1 bets</font>, CO calls, Hero....

(In other words, I am sure CO doesn't have a made flush or straight at this point, but other than that, who knows.)

My spade outs are obviously poisoned leaving me only six, but I can be sure of at least one call if I do make it on the river. What'll it be?