What is the main idea of this presidential proclamation?
A. Dr. King challenged America to recognize that its individual liberty relies upon Americans' common equality.
B. Although great strides have been made to reach Dr. King's "promised land," there is still work to be done to make America a better nation.
C. The strength of Dr. King's leadership was matched only by the power of his words.
D. Dr. King believed this was life's most urgent and persistent question: "What are you doing for others?"