b
(b) For demodulation \(\frac{1}{{{f_c}}} < < RC\) \(\frac{1}{{{f_c}}} = \frac{1}{{100 \times {{10}^3}}} = {10^{ - 5}}s\)

\(RC = {10^3} \times 10 \times {10^{ - 12}}s \) \(= 10^{-8} s \)

We see that \(\frac{1}{{{f_c}}}\) here is not less than \(RC\) as required by the above condition. Hence, this is not good.