This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Respiratory System, Subject name: Pediatrics
"Loeffler's syndrome" is characterized by: 
Select and explain. 
A. Transient, migratory pulmonary infiltrations, B. Fibrosis in the pulmonary apices, C. Fibrosis in the base of one or both lungs, D. Miliary mottling
A: Transient, migratory pulmonary infiltrations
Answer: A: Transient, migratory pulmonary infiltrations 
Explanation: a. Transient, migratory pulmonary infiltrations(Ref: Nelson 20/e p 2080)Loeffler's syndrome is now called "transient pulmonary infiltrates with eosinophilia syndrome" and is most commonly caused by Ascaris lumbricoides or roundworm.