Yet another KK facing resistance

[poboy]

New at table so no reads and have never seen villian before.

PokerStars No-Limit Hold'em, $0.25 BB (9 handed) converter

($21.40)
UTG+1 ($23.25)
MP1 ($9.80)
Hero ($24.65)
MP3 ($25.95)
CO ($17.75)
Button ($18.90)
SB ($25.10)
BB ($65.70)

Preflop: Hero is MP2 with K[img]/images/graemlins/diamond.gif[/img],K[img]/images/graemlins/spade.gif[/img]. I open for $1.25 , folded to CO who raises to $3 , I'm the only caller

Flop: ($6.35) 5[img]/images/graemlins/heart.gif[/img], 4[img]/images/graemlins/diamond.gif[/img], 2[img]/images/graemlins/club.gif[/img] <font color="#0000FF">(9 players)</font>
<font color="#CC3333">Hero bets $5</font>, <font color="#CC3333">CO raises to $14.75</font>, Hero ???

Easy call? Easy fold? Why?