Which one of the following is the ability of a material to absorb moisture from air and thus to dissolve and become liquid?

Explanation:

Deliquescence:

Deliquescence is defined as a physical phenomenon in which a substance (salt or chemical compound) absorbs moisture from the surrounding environment (atmosphere) and eventually dissolves in it, forming a solution (liquid solution). Deliquescent meaning can be said as a tendency of a substance to become liquid.

Hygroscopicity:

Hygroscopicity is the tendency of a solid substance to absorb moisture from its surrounding environment (atmosphere). Hygroscopic substances (like lime) have a strong affinity for water molecules and can attract and retain water vapor.

Capillarity:

Capillarity is a phenomenon by which a liquid (depending upon its specific gravity) rises into a thin glass tube above or below its general level. This phenomenon is due to the combined effect of cohesion and adhesion of liquid particles.

Wilting:

The wilting point or permanent wilting point is defined as the amount of water per unit weight or per unit soil bulk volume in the soil, expressed in percent, that is held so tightly by the soil matrix that the roots of plants cannot absorb this water and a plant will wilt.

Hence option (1) is the correct answer.