PokerStars - €2 NL (6 max) - Holdem - 5 players
Hand converted by PokerTracker 4: http://www.pokertracker.com

SB: 32.25 BB
Hero (BB): 100 BB
UTG: 101.5 BB
CO: 152.16 BB
BTN: 100 BB

SB posts SB 0.5 BB, Hero posts BB 1 BB

Pre Flop: (pot: 1.5 BB) Hero has Jc Jd
UTG raises to 3 BB, CO raises to 9 BB, fold, SB calls 8.5 BB, Hero ?

MP and CO are regs, SB is a fish.
MP opens 17% in that position, CO 3bet vs MP 5.2%. SB is a 72/7.

What should hero do there? fold,call or cold 4bet (in that case, what size?) ?