Nl2 Fr A5

Hand converted with online PokerStrategy.com hand converter:

Leosztás lejátszása

$0.01/$0.02 No-Limit Hold'em (9 handed)

Known players:
[tg]UTG2$1.42:///////;MP1$2.00:///////;MP2$2.53:///////;MP3$2.08:///////;CO$4.77:///////;BU$2.72:///////;SB (Hero)$2.13:///////;BB$2.00:///////;UTG1$1.39:///////;[/tg]

Preflop: Hero is SB with A:d, 5:s.
5 folds, CO calls $0.02, BU folds, Hero raises to $0.10, BB folds, CO calls $0.08.

Flop: ($0.22) 6:s, 9:h, 2:c (2 players)
Hero checks, CO checks.

Turn: ($0.22) A:h (2 players)
Hero checks, CO bets $0.10, Hero calls $0.10.

River: ($0.42) 5:h (2 players)
Hero checks, CO bets $0.40, Hero ??

Hi!

Villain was loose and a little passive!
What would be the most optimal step on the river?

Thanks, N.