将M路频率范围为0.3~4KHz的语音信号用FDM方式进行传输,则采用AM、DSB.SSB调制方式时最小传输带宽分别为()KHz
·8M,8M,4M;
·8M,8M,4M;
·4M,8M,4M;
·4M,8M,8M;