What is the transfer function of magnitude squared frequency response of the normalized low pass Butterworth filter?

• A. ( frac{1}{1+(s/j)^{2N}} )
• B. (1+( frac{s}{j})^{-2N} )
• C. (1+( frac{s}{j})^{2N} )
• D. ( frac{1}{1+(s/j)^{-2N}} )