Final answer:
Water and refrigerants are generally more efficient cooling media than air or oil because of water's high specific heat, and refrigerants' phase change properties, which allow for efficient heat transfer.
Step-by-step explanation:
The efficiency of a cooling media in transferring heat is largely determined by its specific heat and its thermal conductivity. While air is commonly used in cooling because of its availability, it is not the most efficient at transferring heat compared to other substances due to its lower thermal conductivity. Water is often used as a coolant in various systems because of its relatively high specific heat and ability to absorb large amounts of heat. Oil is also used in cooling systems, particularly because it can operate at higher temperatures without evaporating. Finally, refrigerants are specially formulated chemicals used in air conditioning and refrigeration; they have properties that allow them to change phase at convenient temperatures, which makes them very efficient at heat transfer.