The correct answer is: **d) Band Pass Filter** **Explanation:** - A PAM (Pulse Amplitude Modulation) signal consists of pulses at a particular frequency and its harmonics. - To detect or extract the desired PAM signal from noise or other signals, a **Band Pass Filter** is typically used. This filter allows frequencies within a certain range (the bandwidth containing the PAM signal) to pass and attenuates frequencies outside that range. So, **Correct option: d) Band Pass Filterd**

The other options are incorrect for the following reasons: a) **High Pass Filter** - A high pass filter allows signals with frequencies above a certain cutoff to pass. - It is not suitable for detecting PAM signals because PAM signals occupy a specific band of frequencies, not just high frequencies. Using a high pass filter alone would exclude the lower frequency components necessary for proper detection. b) **Low Pass Filter** - A low pass filter allows signals with frequencies below a certain cutoff to pass. - While it can be used to smooth or demodulate certain signals, it does not effectively isolate the PAM signal's bandwidth. It may eliminate important frequency components of the PAM signal, making it unsuitable for detection. c) **All Band Pass Filterd** (assuming this is a typographical error for "All Band Pass Filter") - This term is unclear. If it refers to an "All Band Pass Filter," it could be interpreted as a filter that passes all frequencies, which is not practical. - A proper band pass filter is designed to pass a specific frequency range, which is necessary for detecting a PAM signal. An "all" band pass would not discriminate the signal of interest. **e) none of them** - This is incorrect because a band pass filter is indeed used to detect PAM signals, making option d) correct. **Summary:** - **Correct choice:** d) Band Pass Filterd - **Reason:** It selectively passes the frequency band where the PAM signal exists, enabling effective detection and demodulation.