Answer:
Coffee, tea and sodas have no oils in their composition and so stains can easily be removed with water. On the other hand, candle wax, salad dressing and peanut butter have oils in their composition making their stains harder to remove with water.
Step-by-step explanation:
Water is known as a universal solvent because a lot of substances dissolve in it. However, this does not happen with all substances, as shown in the case of oil. As you may already know, water and oil do not mix, so it is so difficult to remove stains caused by oils or substances that contain oils in their composition. An example of this is the stains caused by candle wax, salad dressing and peanut butter, which because they have oil in their composition, are not easily removed with water and special treatment (usually based on some detergent) is required to clean them.
On the other hand, coffee, tea and soda stains do not have oil in their composition, so they can be easily removed with water.