Answer:
LiOH
Step-by-step explanation:
Just by looking at the answer choices, you can tell which one is the odd one out.
LiOH is the only choice with a OH- attached to it. By the Arrhenius base definition, bases have OH- groups attached to them.
In contrast, by the Arrhenius acid definition, acids have H+ protons attached to them. As we can see from the other three answer choices, they all have an H: HCl, HF, HBr.
Thus, the answer is LiOH.
Hope this helps!