Sergei is a consultant who just joined a multinational company, where he will be leading the business unit. On his first day, he wants to send out a letter to all the members of the team outlining his vision for the group and the products they build. Which form of communication should Sergei use to send this letter?

A$.$

Formal Report

B$.$

Post$-$It Note

C$.$

Email

D$.$

Progress Report