AA getting raised on river by passive player

[B_ing]

UTG is 39/0/0.6 after 60 hands

Pacific Poker
Limit Holdem Ring game
Limit: $0.25/$0.5
10 players
Converter

Pre-flop: (10 players) Hero is Button with A[img]/images/graemlins/diamond.gif[/img] A[img]/images/graemlins/club.gif[/img]
UTG calls, 3 folds, MP2 calls, 2 folds, <font color="#cc0000">Hero raises</font>, SB calls, BB folds, UTG calls, MP2 calls.

Flop: 7[img]/images/graemlins/diamond.gif[/img] Q[img]/images/graemlins/club.gif[/img] J[img]/images/graemlins/club.gif[/img] (9SB, 4 players)
SB checks, UTG checks, MP2 checks, <font color="#cc0000">Hero bets</font>, SB calls, UTG calls, MP2 folds.

Turn: 6[img]/images/graemlins/diamond.gif[/img] (6BB, 3 players)
SB checks, UTG checks, <font color="#cc0000">Hero bets</font>, SB calls, UTG calls.

River: 4[img]/images/graemlins/diamond.gif[/img] (9BB, 3 players)
<font color="#cc0000">SB bets</font>, <font color="#cc0000">UTG raises</font>, Hero ?? is this a fold or call?