As you look up to see who or what, that question is quickly answered with a loud thud and a violent rattling of the door followed by their bloody fists pounding the door. The red liquid smears on the window and you already know it's aware if your presence.
As luck would have it, none of those other things seem to be aware of you.
There's a loose bar close by. Loose enough that even a scrawny, noodle-armed guy like you could manage it if you tried hard enough and get a weapon long enough that you don't have to get too close.
You look to the top corner. A vent! That same vent you've been planning to get out of since three days ago when you first got here. You could use the shank you currently wield to loosen the screws, the blades are flat and thin enough to make it work. With your precision and expertise in escaping prisons you could have it ready in minutes if not mere seconds.
As you dart towards the vent, suddenly the power goes out. The lights turn off and you hear a click coming from the door. A chill goes down your spine and you shiver at the realization that the only thing between you and that thing coming in to kill you is its ability to stand strong against the blows of the maniac.
You could crawl through the vent as a safer means of getting out of this stupid cell. But addressing the elephant in the room, there's no light. What little light you have left is coming from dim spare rays penetrating the window and reaching your room. Even if you somehow manage to navigate your way through the darkness and get the screws loose you'd have to rely almost entirely on feeling your way through, which is only truly reliable if you actually know where you're going. You haven't had the time nor the opportunity to study much of the layout and which routes lead where. For all you know, you could end up leaving the pitch black of the vent only to end up in a much tighter spot. And, speaking of time, it takes longer to pull off and the time in your hands is in short supply.
You can instead take the bar and politely open the door to smash the zombie's head in. It takes less time than feeling your way around the screws and considering the commotion, you don't think the rest'll hear it. You could maybe slip away undetected and find an officer or something, as much as you hate those fuckers. You're small enough, and with your experience and skill it shouldn't be too hard. But, there's a very real and high chance for the record of getting spotted by the horde and you really don't want to think about what'll happen if you do. If the option didn't look like suicide before, it sure as shit does now.
But the clock is ticking, the door is shaking and you know for damn sure you can't stay here.
5 ---> Open the door
6 ---> Crawl through the vent.