b. orderthe following modulation types in terms ofspectral efficiency (best to w

b. orderthe following modulation types in terms ofspectral efficiency (best to worse) and explain why (be specific byshowing a number for each representing the spectral efficiency andhow you got it. The correct explanation is what is being asked forhere a simple ordering of best to worse without a correctexplanation will get you no points):QPSK 8-PSK 64-QAM and BPSK. You can assume that r=0 for perfectfiltering.c. describethe OFDM concept (what is it and how it isconceptually done) explain why orthogonality is useful and whatmakes OFDM better able to work well for higher bandwidths?