Big Blind defense

You're in the big blind (BB) and a player has open-raised from another position. The action reaches you and you have 3 options: re-raise (3-bet), call to see the flop, or fold.

Since you already posted the blind by force, you get a 'discount' on the price to continue, so you defend much wider than from other positions. And you defend even more the later the opener raised: against a BTN (who opens loose) you hold with many hands; against UTG (who opens strong) you're more selective.