All of These Statements Describe Properties of Sodium

All of these statements describe properties of sodium. Which one describes a physical property of sodium?

A) Sodium's surface turns black when first exposed to air.
B) Sodium is a solid at 25°C and changes to a liquid when heated to 98°C.
C) When exposed to water, sodium reacts violently and a gas is formed.
D) When placed in contact with chlorine, sodium forms a compound that melts at 801°C.
E) If solid sodium is put in ethanol, it will produce hydrogen gas.