Magnitude spectrum for discrete-time signals
This looks like a HW problem, so I can only give you a hint. Recall how the sampling process works - it's a convolution with a spike train i.e. a sequence of Dirac delta functions spaced at $F_s$. So the analog spectrum (that you derived in part (a) of the problem) gets replicated many many times centered around integer multiples of $F_s$. Also be careful about aliasing - if the largest frequency in your analog signal exceeds $F_s/2$ it means that this replication process will leak signal energy into the lower frequencies (draw a picture and convince yourself of this).
Finally, analog frequencies in the interval $[-F_s/2, F_s/2]$ get mapped to digital frequencies in the interval $[-1/2, 1/2]$.