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: Pathology
Alarm clock headache is a feature of: 
Select and explain. 
A. Trigeminal neuralgia., B. Sphenopalatine neuralgia, C. Horner's syndrome., D. Glossopharyngeal neuralgia
B: Sphenopalatine neuralgia
Answer: B: Sphenopalatine neuralgia 
Explanation: None