Marginal spot. River call or fold?? 20NL

[Fulzgold]

DO YOU CALL OR FOLD HERE ON RIVER AND WHY?
$0.1/$0.2 No Limit Holdem
4 players
Converted at weaktight.com

Stacks:
CO (<font color="#0000cc">$23.65</font>)
BTN (<font color="#0000cc">$10.48</font>)
Hero (<font color="#0000cc">$20.83</font>)
BB (<font color="#0000cc">$19.92</font>)

Pre-flop: ($0.3, 4 players) Hero is SB T[img]/images/graemlins/heart.gif[/img] T[img]/images/graemlins/club.gif[/img]
CO calls $0.2, <font color="#777777">1 fold</font>, <font color="#cc0000">Hero raises to $1.2</font>, <font color="#777777">1 fold</font>, CO calls $1

Flop: 2[img]/images/graemlins/heart.gif[/img] 9[img]/images/graemlins/diamond.gif[/img] 9[img]/images/graemlins/spade.gif[/img] ($2.6, 2 players)
<font color="#cc0000">Hero bets $1.5</font>, CO calls $1.5

Turn: 3[img]/images/graemlins/heart.gif[/img] ($5.6, 2 players)
Hero checks, CO checks

River: K[img]/images/graemlins/heart.gif[/img] ($5.6, 2 players)
Hero checks, <font color="#cc0000">CO bets $2.8</font>,