Answer:
D: There have been at least eight periods in earth's history
Explanation:
It was to protect its members from employer retaliation.
U.S. Supreme Court ruled on March 3, 1919, that the freedom of speech protection afforded in the U.S. Constitution's First Amendment could be restricted if the words spoken or printed represented to society a "clear and present danger."
I believe the answer is D. MlK was fatally shot while standing on his hotel patio after giving a speech.
