I would prefer a bit of a mix of A), B), C), D), and E).
Not only would killing Jacob be pointless, it would also worsen your chances. He's alright with a rifle, and you don't know what he knows. Or at the very least, you lose bait.. Just kidding.
You should ask Jacob what he knows about the outbreak and specifics of anything about its occurrence if he knows. Ask about the zombies in general, but be sure to include the different kinds. Of course you should ask him about his plans to get any input on what we should do. Never hurt anybody.
As for the D) part, here's what to do. It's a shame we don't have a map. Maybe Jacob has one?
You should mention how you can't stay on that roof forever, and eventually we'll need to move. You should ask him if he has any sort of medium of transportation, [I hope the roads aren't filled with wreckage] useful survival knowledge,
A MAP, or weapons cache as he is a gun enthusiast. The first step to finding a new place to hole up in would be to find a defensible place, plan your route, decide what to take, and how to transport it.
I suggest if he does not have a truck [has to be a truck or big SUV, not a tiny little car] and neither of you can hotwire a car, we're screwed. But maybe we can find an abandoned truck with a set of keys in it still on our exit or in a scouting mission. Once the way has been planned out, the best way to get things into the truck would be to have it on a raised platform, maybe on a lower part of the building outside if you can. Then lower things down by rope while one person is down there to load it in back; strap everything down in case of a wild ride. If you can't get it on a raised platform, have some sort of harness set up where in case of emergency the person below can be raised up at a moments notice at the very least above the zombies reach. Take out the zombies, and get back to business. [Repeat] This is where a map would come in handy very much.
If there is no map, and one cannot be found, then ask him or yourself if you know the locations of any office buildings, warehouses, shipyards, or maybe even hospitals nearby.
And I completely forgot about maintaining weapons when I wrote that. xD
If you can do that while talking, please do. If not, do it after.
I had also watered and set out the plant seedlings in the sun- lettuce wouldn't be too filling unfortunately. We had to decide our next course of action.
I can't believe I didn't say something earlier but where did we get the dirt to plant this? Is there some sort of dirt structure already up here? I don't mean to be a prick at pointing this out. Plus, it doesn't seem like it has been a very big factor in our actions anyways.