Plot the following and determine whether they are continuous-time or discrete-time signals (a) x(t) = cos(5t), (b) x(t) = sinc(t) = sin(t) (c) x(t) = e* sin(2t), (d) x[k] = cos(2kt), t t = [0,1] tR t [0, ) k N, t = 0.1 1, (e) x[k] = 0, if k = [2, 1, 0, 1, 2] else k Z