$5.50 PokerStars Middle pair facing 4-to-1 River Bet

[Draidin]

I flop middle pair on an Ace high rainbow unraised flop.
BB is passive and got his big stack from an all-in confrontation when he flopped a house against someone's trips.
I have maybe raised once or twice to this point and mostly been limping with suited connectors. And have won a couple of show downs and lost 1 or 2. Won a couple of uncontested pots too.

Poker Stars, $5 + $0.50 NL Hold'em Tournament, 50/100 Blinds, 5 Players
LeggoPoker.com - Hand History Converter

UTG: 3,595
<font color="blue">DRAIDIN</font> (CO): 1,685
BTN: 1,515
SB: 1,790
BB: 4,915

Pre-Flop: (150) 8[img]/images/graemlins/spade.gif[/img] 7[img]/images/graemlins/spade.gif[/img] dealt to <font color="blue">DRAIDIN</font> (CO)
UTG folds, DRAIDIN calls 100, BTN calls 100, SB calls 50, BB checks

Flop: (400) 2[img]/images/graemlins/spade.gif[/img] A[img]/images/graemlins/diamond.gif[/img] 8[img]/images/graemlins/heart.gif[/img] (4 Players)
SB checks, BB checks, <font color="blue">DRAIDIN</font> <font color="red">bets 200</font>, 2 folds, BB calls 200

Turn: (800) K[img]/images/graemlins/spade.gif[/img] (2 Players)
BB checks, <font color="blue">DRAIDIN</font> <font color="red">bets 385</font>, BB calls 385

River: (1,570) 4[img]/images/graemlins/heart.gif[/img] (2 Players)
<font color="red">BB bets 400</font>
<font color="blue">DRAIDIN</font> ???

Bet or call the turn? River???