The value of α in the attenuation band of constant k-low pass filter is?

• A. α=2 cosh-1⁡(fc/f)
• B. α=cosh-1⁡(f/fc)c) α=2 cosh-1⁡(f/f
• C. α=2 cosh-1⁡(f/fc)
• D. α=cosh-1⁡(fc/f)