Select the correct answer.

Which statement best describes the properties of covalent compounds?

A. They are always solid at room temperature, are brittle, and have a high melting point.
B. They may be gases, liquids, or solids at room temperature, and have a low melting and boiling point.
C. They are always composed of an equal proportion of cations to anions.
D. They are always liquid at room temperature, and have a high melting and boiling point.
E. They are good conductors of heat and electricity, and are ductile and malleable.