What is the sampling frequency of the system, the sampling period of the A/D is 10 ms; where the input is xa(t) = 5 cos 100nt +2 sin 200nt. O a. 100 Hz O b. 25 Hz O c. 200 Hz O d. 50Hz The convolution of sampling frequency and reconstruction filter is digital frequency O a. Sampled signal. O b. Train of impulse. O c. Digital signal. O d. Orignal signal. The function given by the equation x(n) = 1, for n20; x(n) = 0, for n=0 is a: O a. Unit pulse signal O b. Unit ramp signal O c. Unit impulse signal O d. Unit step signal