Which of the following best describes the "Sound of Freedom"?
a. A phrase often used in various media and literature to symbolize the ideals and values associated with freedom and liberty.
b. The title of a film or media production that explores themes related to human rights and social justice.
c. The sound emitted by freedom-related public events, such as protests or demonstrations, that symbolize societal change.
d. A specific audio frequency used in sound therapy to promote relaxation and mental well-being.