In the 1960s, the Federal Communications Commission made two important decisions: 1) they authorized the process of broadcasting two signals simultaneously on a single channel, making stereo broadcast possible, and 2) they ruled that FM programming in cities with a population greater than 100,000 had to differ from AM programming at least 50 per cent of the time. What was the result of this, in terms of radio programming? it greatly increased the importance of FM for Rock music, and encouraged the development of more "progressive rock" stations it greatly decreased the number of FM stations playing Rock music, and led to an emphasis on talk radio it led to a great increase in the number of stations featuring continuous religious programming