Answer:
light of human conscience
Type of figurative language:
Metaphor
Meaning of figurative language:
Just as the human conscience always reminds us of the truth it is compared to light because of its transparency.
Effect on tone and mood:
It has a serious tone and creates a solemn mood
Effect on audience:
It makes the audience reflect on their conscience which tells them that injustice is wrong as illuminating and right.
Step-by-step explanation:
A Metaphor is a figurative language that links an object directly to another. The reason why a metaphor is used is to make the audience imagine what the author is talking about.
Since the object being linked to the words the author wishes to use is very relatable to the audience, it makes the thoughts easier to convey and more real to the audience. This is what Martin Luther King aims to achieve when he linked light to the human conscience.