单项选择题

A、M<a1fcbf'hf'(ho-hf'/2)或fyAs≤a1fcbf'hft    
B、M>a1fcbf'hf'(ho-hf'/2)或fyAs≤a1fcbf'hft    
C、M≤a1fcbf'hf'(ho-hf'/2)或fyAs=a1fcbf'hft