In the 1920s, the development of practical radio communication was furthered by the theory of modulation. the use of vacuum tubes. its ability to receive more than just simple pulses. both the theory of modulation and the use of vacuum tubes. All these answers are correct.
In the 1920s, the development of practical radio communication was furthered by
the theory of modulation.
the use of vacuum tubes.
its ability to receive more than just simple pulses.
both the theory of modulation and the use of vacuum tubes.
All these answers are correct.