I can't really 'vote' because none of the above really apply to me.
In the car, Masi is quiet as a church mouse, but a stranger touching the car or trying to get in it, all bets are off.
Stranger comes to my house, again, quiet, alert, watchful, will react off my que, and has never had a problem letting a stranger IN when I am present.
Out in public, again, alert/watchful/I would say suspicious of strangers, I've never been in a situation where I've need 'protection' so I couldn't say how she'd react to a threat, but I think I know.
I would say Masi is a very 'possessive' dog of me. Protective? Again haven't been in the situation to test that out. I know I've had strangers to her, come at me flailing arms /loud/boisterous and she has "gone" off on them (barking)..Perceived threat? Maybe.
Do I expect her to protect me? No, I protect her