In the following question, out of the four alternatives, select the alternative which is the best substitute of the phrase.The process by which air is circulated through, mixed with or dissolved in a liquid or substance.

* Aerating is the process by which air is circulated through, mixed with or dissolved in a liquid or substance.Miasma refers to an oppressive or unpleasant atmosphere or an unhealthy vapor.Effluvium refers to an unpleasant or harmful odor or discharge.Volatile means liable to change rapidly and unpredictably, especially for the worse, or easily evaporated at normal temperatures.