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
Feature (s) of syringomyelia is/are -a) Dissociated sensory lossb) Wasting of small muscles of handc) Ascending weaknessd) Frequent bladder- bowel involvement 
Select and explain. 
A. ac, B. ab, C. ad, D. bc
B: ab
Answer: B: ab 
Explanation: None