This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Pharmacology
Which of the following show Regressive metamorphosis? (NOT RELATED) 
Select and explain. 
A. Hydatid cyst, B. Cysticercoid, C. Cysticercus bovis, D. Cysticercus cellulosae
A: Hydatid cyst
Answer: A: Hydatid cyst 
Explanation: .