No reads. Your move?

PartyPoker, Big Blind is t15 (10 handed) Converter on pregopoker.com

UTG (t960)
UTG+1 (t785)
MP1 (t775)
MP2 (t770)
MP3 (t795)
Hero (t770)
CO (t785)
Button (t530)
SB (t720)
BB (t1110)

Preflop: Hero is in CO+1 with K[img]/images/graemlins/heart.gif[/img] A[img]/images/graemlins/heart.gif[/img]
UTG calls t15, <font color="red">UTG+1 raises t50</font>, <font color="red">MP1 raises t150</font>, <font color="gray">MP2 folds</font>, <font color="gray">MP3 folds</font>, <font color="blue">Hero ???</font>