You are presented with the question "What causes edema?" and the following answer choices: 
- An infection
 - amoebae
 - heating liquids
 - An antibiotic
 - smoking
 - Vitamins
 - prolactin release
 - Food poisoning

Now knowing that infection can cause bodily tissues to swell and doctors call such tissue swelling edema, choose the best answer.


 

 An infection        