If the characteristic equation of a feedback control system is given by s4 + 20s3 + 15s2 + 2s + k = 0 Then the range of values of K for the system to be stable will be

• A. 1 < K < 2.49
• B. 0 < K < 1.49
• C. 1 < K < 4.49
• D. 0 < K < 3.49