To Say That Death Was a "Taboo Topic" in American

To say that death was a "taboo topic" in American society during the 1960s and early 1970s means that:

A) A fundamental and defining aspect of human life had largely been removed from investigation and critical study.
B) This subject is a branch of "thanatology."
C) This topic is most closely associated with sorcery and witchery.
D) All of these
E) None of these