option 4 for me. BTW, per the game rules "I have knife"
Odds are that if the owner of the truck left and left the done lights on, and left the guns behind he is out taking a wizz and will be right back. One might have to question the logic of having so many guns in one vehicle, so there might entertain the possibility that there are other people traveling with him. I would bet that he took the keys with him, but given the possibility of other people traveling with him and that any one of them could be armed the last thing I would want to do is create a lot of noise by starting a car by key or hotwiring it.
A gun is a rather simple device to make, so I don't need all 3-and it may be difficult to carry all three and get away both quickly and safely. Perhaps the simplest home made guns to make are the shotguns/rifles so they are of low value to steal in the first place, and the ones pictured don't strike me as a kind that can reload quickly. Also carrying a rifle/shotgun everywhere would likely be heavy, and kind of make me stand out to any sniper who may want another firearm or more ammo for any posses that have formed-or anyone who plans to take advantage of me while I sleep. So the pistol I would take, and of course I would need ammo (any gun without ammo is kind of worthless, except to threaten), for it can be easily concealed, it's lightweight, and can hold more ammo per reload.
and watch it be a manual/stick-not an automatic transmission.