Douglass used formal diction to establish ethos.
Formal diction refers to the careful selection of words that are polite, concise and uses a formal language in order to pass across a message.
In this example given, words such as "eloquent", "fluent", and the accurate use of the words and the way that the message was passed across showed that Douglas used a formal diction.
Therefore, the correct option is B.
Read related link on:
https://brainly.com/question/11207638