Final answer:
Malcolm X used the 'powder keg' metaphor to address the volatile mix of racial tensions, social injustice, and economic inequality faced by African Americans, highlighting the potential for explosive social unrest.
Step-by-step explanation:
Malcolm X said that his listeners were sitting on a powder keg because of the combination of racial tensions, social injustice, and economic instability prevalent in the United States at the time. This metaphor was used to describe the explosive potential of anger and frustration resulting from years of oppression, discrimination, and limited economic opportunities for African Americans. His rhetoric served as a clarion call to awaken those suffering from the historical trauma inflicted by slavery and Jim Crow laws to their plight and to the persistence of segregation and economic inequality, despite the civil rights advancements of the era. The 'powder keg' symbolized the imminent danger of a social explosion stemming from the continual repression that could no longer be ignored.