An ionic compound that attracts atmospheric water so strongly that a hydrate is formed is said to be :

An ionic compound that attracts atmospheric water so strongly that a hydrate is formed is said to be : hygroscopic.

Some compounds are prone to hydrate formation as a result of absorbing moisture molecules from their environment. hygroscopic is the term for this characteristic. Extreme hygroscopic is referred to as deliquescence when the amount of moisture absorbed is so great that the substance itself dissolves in the water absorbed. $\mathrm{Ex}:{\mathrm{ZnCl}}_2\text{ and }{\mathrm{CaCl}}_2$

Hence, option B is correct.