We must consider that acid is related to the H+ cations and the bases to the OH- anions. By definition, that substance that releases OH- will be considered a base. So an Arrhenius base is any species that increases the concentration of OH- in aqueous solution, as is the case of NAOH which in aqueous solution releases its OH- anions.
The answer will be: When Arrhenius bases interact with water it will release OH- ions
