A random noise process has a PSD which is constant K within bandwidth W and zero elsewhere. A square wave oscillating between A and B is added to a sample function of this random process to form Z(t). The signal power of Z(t) (mean square value) is O a. KW + (A? + B?)/4 O b. KW(A + B)/2 O c. KW + (A + B)/2 O d. KW + (A? + B?)/2