Final answer:
Martin Luther King, Jr. was focused on advocating for economic equality through the Poor People's Campaign and supporting the sanitation workers' strike in Memphis, championing human dignity and nonviolent protest up to the time of his assassination.
Step-by-step explanation:
At the time of his assassination, Martin Luther King, Jr. was focused on supporting sanitation workers in Memphis, Tennessee, who were trying to unionize and fighting for their dignity with the slogan 'I AM A MAN.' This was part of a broader initiative known as the Poor People's Campaign, which sought to address economic inequalities affecting all poor Americans, regardless of race, and to pressure Congress for legislative change. Dr. King advocated for nonviolent protest and civil disobedience, following the practices he admired from figures like Mohandas Gandhi. His last speech in Memphis on April 3, 1968, underscored the determination to reach the 'Promised Land' of racial and economic justice, despite the rising threats against his life.