15. Consider a continuous-time system with the closed-loop transfer function

T(s)= S s+4s+8 Using a zero-order hold on the inputs and a sampling period of 7 = 0.02 s, determine which of the following is the equivalent discrete-time closed-loop transfer function representation: 0.019z -0.019 a. T(z): b. T(z)= z + 2.76 0.87z + 0.23 z2 0.14z+0.24 - 0.019z -0.019 c. T(z) = z-1.9z + 0.9 0.043z -0.02 d. T(z) = z+1.9231