The compound that is not a dehydrating agent is CaCl2 (hydrated calcium chloride).
While anhydrous CaCl2 (calcium chloride) is a dehydrating agent, hydrated CaCl2 (calcium chloride with water molecules attached) does not have the same ability to absorb water.
All of these compounds are alcohols, but the shorter the carbon chain, the more soluble they are in water.
Ethanol (C2H5OH) has the shortest carbon chain among the options, making it the most capable of forming hydrogen bonds with water molecules, thus leading to higher solubility.