Answer:
From the presented words, only Y'all is a coloquialism.
Step-by-step explanation:
Colloquialisms are words employed in informal contexts that have undergone a modification to be used in spoken and written contexts without changing in any of them. In other words, they preserve their form. However, the preserve logic and syntactic order instead of the only letter like IDK, or NAFTA. Dog is not a colloquialism because of it as a formal recognized word or concept. So, our only option is Y'all.