The prefix in the word 'impartial', meaning 'unbiased', is im-. Without that prefix, partial means biased. Im- is a prefix that gives a word its opposite meaning.
I think it’s a. the use of bolding, font size, and headlines
The words in the brackets are telling the actors what to physically do, meaning it would be a stage direction.
It isn't dialogue because that is a conversation between two people.
It isn't dialect because that is how a person speaks. There is no speaking in the brackets.
It isn't narration because it isn't spoken allowed for the audience.
It isn't a description because that is too broad a term more often used for emotions.
