ANS:D - soluble in liquid state.

In an eutectic system, two elements are completely soluble in liquid state. In a eutectic system, when a specific composition of two or more elements or compounds is cooled, a eutectic mixture is formed. This mixture has a lower melting point than any of the individual components. During solidification, both elements or compounds are completely soluble in the liquid state, but when they solidify, they form a mixture with a specific composition where the constituents are usually insoluble in each other in the solid state. This leads to the formation of a distinct microstructure, often characterized by a lamellar or fibrous structure. Therefore, in a eutectic system, the two elements are soluble in the liquid state, but insoluble in the solid state.