Final answer:
Hygroscopic salts increase temperature when they absorb water.
Step-by-step explanation:
The correct answer is (b) Increases temperature.
Hygroscopic salts are substances that have the ability to attract and hold water molecules from their surroundings. When hygroscopic salts absorb water, it undergoes an exothermic process, which means heat is released. This release of heat increases the temperature of the surroundings, resulting in an increase in temperature.
For example, when calcium chloride (CaCl2), which is a hygroscopic salt, comes in contact with water, it absorbs the water vapor from the air and forms hydrated crystals. This process releases heat, causing an increase in temperature.