All alkalies are bases but all Bases are not alkali.

The basic chemicals that are soluble in water and alkalis are typically referred to as bases, and the hydroxide ions that these bases contain give alkalis their characteristic features. Not all bases, nevertheless, are water-soluble. Take this as an example:
CuO, a basic metallic oxide that may neutralize acids, cannot dissolve in water and cannot be referred to as an alkali because of this.
Therefore, it can be said with certainty that all bases are not alkalis but all alkalis are bases.

According to acid-base concepts, any substance that is a proton acceptor is called the base. An alkali is a basic substance that when dissolved in water gives hydroxide ions. Hydroxides of copper and zinc are bases but they are insoluble in water. So they are not alkali. Thus given statement is true.

Hence, option A is correct.