Final answer:
The given compound KOH (potassium hydroxide) is an Arrhenius base because it dissociates in water to yield hydroxide ions, which is the defining characteristic of an Arrhenius base.
Step-by-step explanation:
The question asks which of the given compounds is an Arrhenius base. An Arrhenius base is a substance that dissociates in an aqueous solution to produce hydroxide ions (OH-). Reviewing the options, compound KOH (potassium hydroxide) fits this definition as when dissolved in water, it dissociates into K+ and OH- ions. The other compounds provided do not meet the criteria for an Arrhenius base as they do not dissociate to yield hydroxide ions in aqueous solution. Therefore, the correct answer is C) KOH.