Answer: they were marks at particular heights over the words of the song
Explanation:
They told the singer what pitch to sing.
They date back almost 40,000 years, I hope that helped :)
Around the mid 1940s in the united states
Answer:
A
Explanation:
"The case of actress Jean Muir marked the first and most famous indication of Counterattack’s influence. In August 1950, only weeks after the publication of Red Channels, Theodore Kirkpatrick of American Business Consultants discovered that Muir was scheduled on August 27 to appear on the NBC-TV sitcom The Aldrich Family, despite her sizeable entry in Red Channels."
For the question what are the songs for the question