Three.
The tradition began with the current Queen's grandfather, King George V, in 1932.
When he died, his eldest son, King Edward VIII, did not deliver a Christmas message due to his abdication of the throne.
Edward's younger brother, King George VI, resumed the practice (albeit sporadically at first).
After George's death, his daughter, Queen Elizabeth II, who is the current Queen of England, continued the tradition set by her father.
So in total, that gives us three monarchs who have delivered a Royal Christmas Message:
1) George V
2) George VI
3) Elizabeth II
A representative democracy would involve Representatives, who were elected by citizens, deciding laws
Yes •Workers made products in large factories.
No •Workers had to become highly skilled.
Yes •Workers used machines for repetitive tasks.
Yes •Workers made products on a large scale.
No •Workers earned considerably more money.
No •Workers made products out of their homes.
Polyphony began and musical rules changed
The tritone is argued as a musical interval composed of three adjacent whole tones. It is often defined as an interval spanning six semitones. it led to the disregard of traditional tonality.