Which of the following statements is true?

Non-metals generally lack ductility (cannot be drawn into wires), so all non-metals are non-ductile is a correct generalization. Not all metals are solids—mercury is a liquid metal at room temperature. Not all metals are hard—sodium and potassium can be cut with a knife. Not all non-metals are gases—iodine, sulfur, and carbon are solid non-metals, and bromine is liquid. The defining property of non-ductility for non-metals makes option (4) correct.