You are the Office 365 administrator for your company.
The company requests that you implement a document collaboration and social networking solution that meets the following requirements:
Users must be able to join groups to receive project updates.
Any user must be able to post an event.
You need to implement a solution.
Which solution should you implement? members who belong to the same email domain. This unique feature provides corporate employees with the ability to communicate privately, using a graphical user interface (GUI) that resembles Facebook.

A.
Microsoft SharePoint document libraries

B.
Microsoft Yammer

C.
Microsoft OneDrive for Business

D.
Microsoft SharePoint newsfeeds

Explanation:

Yammer is Microsoft’s private collaboration platform for enterprise social networking.
Unlike public social media platforms such as Twitter, Yammer only allows members to connect with other
References: https://about.yammer.com/product/features/