单项选择题

函数的傅里叶展开式中的a0=(    )
   A.-π    B.0    C.π   D.2π

A.174.24.96:6088/Latex/latex.action?latex=Zih4KT1cbGVmdFx7XGJlZ2lue2FycmF5fXtjY314LCAmLVxwae%2B8nHhcbGVxMCBcXC14LCAmMO%2B8%0D%0AnHhcbGVxXHBpXGVuZHthcnJheX0%3D'
B.-π
C.0
D.π