I would contend with the ideal of #4, though not semantically.
No, "a gun" is not essential to the functions your body needs to sustain itself. There is no disease I'm aware of that stems from Vitamin Gun deficiency.
That said, the idea behind buying a gun comes directly from a function essential to life... predator protection.
Banning the sale of firearms is just the first step toward their real goal... banning Slippy Pikes™.
We can't give them an inch.