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: Orthopaedics
Indicator (s) of poor prognosis in the pott's spine is/are -a)  Healed vertebral lesionb) Grade IV pott's spinec)  Kyphotic angle > 60°d)  Short duratione) Acute onset 
Select and explain. 
A. ab, B. bc, C. abc, D. bcd
C: abc
Answer: C: abc 
Explanation: None