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) Email
B) Sticky note
C) Progress report
D) Formal report

Email is the most appropriate form of communication for Sergei to use in this scenario because it allows him to quickly and efficiently reach all members of his team with a detailed message outlining his vision. Sticky notes are too informal and limited in space, progress reports are for updating on the status of projects, and formal reports are too detailed and not suited for introductory communications.