An informal writing style is typically appropriate when writing for an infamiliar audience.​

Analytical reports are written for external audiences; informational reports are written for internal. An informal writing style is appropriate for external reports

Explanation:

Meaning of Informal Writing Style

Colloquial – Informal writing is similar to a spoken conversation. Informal writing may include slang, figures of speech, broken syntax, asides and so on. Informal writing takes a personal tone as if you were speaking directly to your audience (the reader).

I hope that this helps you

answer; /// the correct answer is (shared); /// good luck

b is the correct answer