I went the 5th option.........
I do quite a fair amount of remote travel and carry a firearm (.223) for several reasons,
1.
The law in WA (and other states I believe) state that if you hit an animal, you as the driver MUST contact the wildlife rescue mob. Now, if you're half way up the tanami or GCR or even half way to Broome, the wildlife rescue mob won't come out to you. They (or more than likely get you to) notify the police, who will attend and dispatch said animal. Now, being that some places can be hundreds of km from the nearest town that has a police station, the plods won't bother to attend or will take a day to get to you.
You then have only a couple of options,
Drive the injured critter to the nearest town that has a vet or wildlife rescue place (even if it's hundreds of km in the opposite direction).
Leave the critter to die a horrible death.
Try and bludgeon or use a knife to put it out of misery.
Dispatch it humanely and quickly with a rifle.
I'll go with the 4th option.
2.
As a survival rifle. if all goes pear shaped and help is days away, I can atleast shoot some tucker (if I run out).
3.
Yearling wild goat in the camp oven.....................mmmmmmmmmmmm..........yum...............

4.
Despatching feral animals where allowed (to shoot).
The rifle lives in a locked gun cabinet built into my truck and the ammo and bolt is stored seperately.