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: Medicine
A man presented with bilateral crepitations In the base of the lungs and signs of pneumonitis with a history of exposure to pigeon faeces. What is true about this condition? 
Select and explain. 
A. Diagnosis can be made on the basis of history, B. CT scan is the investigation of choice, C. Chest X-ray will reveal characteristics changes, D. It is a type 1 hypersensetivity reaction
A: Diagnosis can be made on the basis of history
Answer: A: Diagnosis can be made on the basis of history 
Explanation: Patient may developed hypersensitive pneumonitis.