Final answer:
Being a father affected MLK Jr.'s viewpoint by highlighting the negative impact of racism on children's self-concept, which is exemplified when he explains segregation to his own children.
Step-by-step explanation:
In "Letter from Birmingham Jail," being a father has significantly influenced Martin Luther King Jr.'s perspective. His experience as a parent provided him with a profound understanding of the impact of racism on young minds. The most relevant point to this question is captured in his reflection on explaining to his children why they can't go to the public amusement park that has been advertised on television. This conversation is emblematic of a broader societal issue where racism poisons a young person’s self-image and sense of what is possible in their life. Therefore, the correct answer to the question is option D: It has allowed him to see racism can poison a young person’s self-image.