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: Pharmacology
Onabotulinum toxin A can be used for the treatment of: 
Select and explain. 
A. Cervical dystonia., B. Chronic migraine., C. Blepharospasm., D. Strabismus.
B: Chronic migraine.
Answer: B: Chronic migraine. 
Explanation: Onabotilinum toxin A has recently been approved to prevent a headache in adult patients with chronic migraine.