Could There Exist a Proposition, P, for Which There Is

Could there exist a proposition, p, for which there is no corresponding proposition, not-p?

A) Yes, because I and O propositions do not have contraries.
B) Yes, because some propositions are already negative and cannot be negated again.
C) Yes, because some propositions are inherently affirmative and therefore cannot be negated.
D) No, because every proposition has a contrary.
E) No, because every proposition can be contradicted.