What is the general formula that represent the phase of the poles of transfer function of normalized low pass Butterworth filter of order N?

• A. \(\frac{π}{N} k+\frac{π}{2N}\) k=0,1,2…N-1
• B. \(\frac{π}{N} k+\frac{π}{2N}+\frac{π}{2}\) k=0,1,2…2N-1
• C. \(\frac{π}{N} k+\frac{π}{2N}+\frac{π}{2}\) k=0,1,2…N-1
• D. \(\frac{π}{N} k+\frac{π}{2N}\) k=0,1,2…2N-1