For a Given Substance That Exhibits Liquid-Crystalline Properties,the Transition from Solid

For a given substance that exhibits liquid-crystalline properties,the transition from solid to liquid-crystal state occurs ________.

A) over a range of temperatures between the melting point of the solid and the boiling point of the liquid
B) at the melting point of the solid
C) over a range of temperatures that includes the melting point of the solid
D) at a well-defined temperature above the melting point of the solid
E) at a well-defined temperature below the melting point of the solid