All of the listed options could influence an organism's chances of survival and reproduction, but if we are considering which one may not directly lead to natural selection, then “mental impairment” could be the answer.
While mental impairment could affect an organism's behavior and survival, it may not always have a direct impact on reproductive success or the natural selection process in the same way that disease, camouflage, or weakness can.
Thus, the answer is mental impairment.