Which method would be the best to use in order to separate a mixture of water and rubbing alcohol?
a. distillation
b. filtration
c. chromatography

A. Distillation. Distillation is the most widely used technique for the separation of liquids, and in this instance the same applies. Distillation involves the separation of liquids that have two different boiling points in such a way that the one liquid with the lower boiling point will evaporate first. Alcohol has a lower boiling point than water, thus when heat is applied to the mixture, the alcohol will evaporate into a gaseous state first and will then be decanted into a separate container. 

Filtration will not necessarily work as effectively, as rubbing alcohol is miscible in water, which means that the particles of the rubbing alcohol have wedged their way in between the water particles and may not separate once passed through a filter.

There are a variety of chromatography techniques used for separation and analysis, yet most of these techniques are used exactly for the purpose of analysis. This means that the separated liquids are not necessarily recaptured, but rather ionized and analyzed using different methodologies. One chromatography methodology that may apply here is that of ion-exchange chromatography, yet this will not be as effective, as both compounds are fairly non-polar and will have similar retention values.

It changes food into energy that the organism can use.