Q: In this task, you are given a multiple-choice question about healthcare. Answer the question based on your information and classify your answers into '1', '2', '3', and '4'.
Question: The practice of posteroanterior chest x-ray in forced expiration is very useful for the diagnosis of:
Options: <1> Loculated pleural effusion. <2> Pneumothorax minimum. <3> Hemothorax <4> Pulmonary atelectasis. <5> Pericarditis
A:
2