This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endocrinology, Subject name: Medicine
The differentiating feature b/w Ectopic ACTH secretion and Cushing syndrome is - 
Select and explain. 
A. Hypokalemic alkalosis, B. Clinical features of cushing syndrome, C. Hyperpigmentation, D. Hypeension
A: Hypokalemic alkalosis
Answer: A: Hypokalemic alkalosis 
Explanation: ectopic ACTH has no typical Cushing's signs & symptoms and hypokalemic alkalosis is the predominant manifestation ( Harrison 17 pg 2255)