Answer:
The correct answer is D: library books discussing the life of Dr. Martin Luther King Jr.
Step-by-step explanation:
Library books represent the best source we could use to support a written argument about Dr. Martin Luther King Jr.'s achievements, as they were written by experts who dedicated their life to different researches and investigations regarding his life and achievements.
On the other hand, online blogs often cannot be a reliable source of the information, while television programs and interviews about this person can be pretty subjective and adapted to commercial needs.s.