Soluble bases are called:

Alkalis are bases that are soluble. A base that dissolves in water is called alkali. A soluble base solution has a pH higher than 7.0. A weak alkali only partially dissociates to produce hydroxyl ions, whereas a strong alkali totally dissociates. In contrast to aqueous ammonia, sodium hydroxide is a strong alkali. Compounds known as bases are those that take an electron pair from a solution. In liquids, notably water, they can be either soluble, insoluble, or very slightly soluble. It is crucial to understand the similarities and differences between soluble and insoluble bases since both have similar characteristics.

Alkalis are bases that are soluble. A base that dissolves in water called alkali. A soluble base solution has a pH higher than 7.0.

Hence, option C is correct.