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