Which choice describes the type of language that should be used in a formal discussion? O casual words and phrases common in everyday conversation
O facts supported by evidence without any opinion or bias
syntax and diction that are appropriate to the topic and audience
O slang and idioms that show knowledge of modern culture

syntax and diction that are appropriate to the topic and audience

Explanation:

In formal discussion, the subject matter is discussed in such a way that it follows a certain method or procedure. This is why the syntax used and the diction have to be appropriate for the topic discussed and the audience involved so that the relevant procedure is followed.

It is therefore important to carry out research on the type of audience one will be in front off as well as the procedures involved so that the proper etiquette is followed.  

i have 15 more questions to answer and i’m a english person

no, i never do because that’s not the reason for what i speak to or of.