Answer:
Level of formality
Step-by-step explanation:
The aspect of language is most affected by your relationship to your audience is the "level of formality".
When speaking to an audience, what affects that relationship between the speaker and the audience is the level of formality. How the speaker speaks to an audience that's familiar with him will be totally different from how that speaker will speak to an audience that is totally unfamiliar with him.
Therefore, the level of formality affects the relationship with the audience.