Depends on the situation.
Currently? 40 pound box of cake mix I'm probably going to launch at my store manager.
Is it the 40 pound box of cake mix that kills? Or is the person hucking the 40 pound box of cake mix?
The toilet. Lost count of the number of times this has saved me from getting dysentery or something and it's so convenient when it just pushes the shit away from my house and I never have to see or smell it again. I almost feel bad that I repay it for all its done by repeatedly shitting in it.
Probably my hatchet, first aid kit, and a duffel bag I keep packed with all weather gear and a small tent as well as my headlamp, survival knife, and half a dozen MREs
I'm not even a "collapse is imminent" prepper kinda guy but it's better to be safe than sorry, you never know.
I'm outside so I'm not sure how to evaluate "the room". My phone is the most immediate at hand (pun intended) useful thing right now though.
My pc but that's too easy so I choose my bed as the very next thing. Good comfortable sleep is important.
Air. Can’t go more than a minute or two without it, and there’s enough to share!