I saved Duck because he's like ten years old, what the fuck.
And yeah, the Carley/Doug thing? Could have been communicated better. Doug seemed capable enough, but he didn't have a gun and know how to use it, and that alone made saving her a greater priority in this post-apocalypse situation.
Plus she was pretty smokin', and had already done you a solid by knowing what you did and not telling anyone. Like, you have way more connection to and appreciation for Carley as a character than you do Doug. It's not even a contest.
no, you take carley out because she knows too much.