Which of the Following Is True of Hygroscopic Crystals

Multiple Choice

Which of the following is true of hygroscopic crystals?

A) They are anhydrous crystals that become hydrated upon standing in air.
B) They are hydrated crystals that become anhydrous upon standing in air.
C) They are anhydrous crystals that continue to remain the same even when exposed to air.
D) They are hydrated crystals that continue to remain the same even when exposed to air.