No reads, CO seems like a reg.

By zoom experience BB can have a wide range of hands in this situation, but rarely complete air.
Putting MP on overpairs, some % bluffing with overcards and som flushedraws.
Guessing CO only will do this with sets and nutflushdraws?

What should I do?

PokerStars - $0.10 NL FAST (6 max) - Holdem - 6 players
Hand converted by PokerTracker 4: http://www.pokertracker.com

Hero (BTN): 194.4 BB
SB: 365.5 BB (VPIP: 19.05, PFR: 12.70, 3Bet Preflop: 0.00, Hands: 64)
BB: 100 BB (VPIP: 100.00, PFR: 0.00, 3Bet Preflop: 0.00, Hands: 1)
UTG: 219 BB (VPIP: 0.00, PFR: 0.00, 3Bet Preflop: -, Hands: 2)
MP: 417 BB (VPIP: 25.00, PFR: 25.00, 3Bet Preflop: -, Hands: 4)
CO: 100 BB (VPIP: 25.14, PFR: 21.23, 3Bet Preflop: 5.97, Hands: 184)

SB posts SB 0.5 BB, BB posts BB 1 BB

Pre Flop: (pot: 1.5 BB) Hero has 7h 5h
fold, MP raises to 3 BB, CO calls 3 BB, Hero calls 3 BB, fold, BB calls 2 BB

Flop : (12.5 BB, 4 players) 9h 4s 6h
BB bets 3 BB, MP raises to 20.9 BB, CO raises to 97 BB and is all-in, HERO?