Radio became a true mass medium in the decades after the first commercial radio station began operation in the year __________.A.1890B.1860C.1920D.1830

Sure, let's break down the question step by step:

1. Identify the key information needed: The question is asking for the year when the first commercial radio station began operation, which led to radio becoming a true mass medium.

2. Review the options provided:

   • A. 1890
   • B. 1860
   • C. 1920
   • D. 1830

3. Historical context:

   • The first commercial radio station is widely recognized as KDKA in Pittsburgh, Pennsylvania.
   • KDKA began broadcasting on November 2, 1920.

4. Match the historical fact with the options:

   • The year 1920 corresponds with option C.

5. Conclusion: The correct answer is C. 1920.

So, the completed sentence is: "Radio became a true mass medium in the decades after the first commercial radio station began operation in the year 1920."