This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Medicine
A patient with cushingoid features presents with hemoptysis, he shows no response to dexamethasone suppression test. The most likely diagnosis is: 
Select and explain. 
A. Adrenal hyperplasia, B. Adrenal adenoma, C. Ca lung with ectopic ACTH production, D. Pituitary microadenoma
C: Ca lung with ectopic ACTH production
Answer: C: Ca lung with ectopic ACTH production 
Explanation: Ca lung with ectopic ACTH production