You have a Microsoft Office 365 subscription. You plan to upgrade from Microsoft Skype for Business to Microsoft Teams. You use the following workloads in Skype for Business: ✑ Audio/video conferencing ✑ Dial-in conferencing ✑ Enterprise Voice ✑ Persistent Chat ✑ Chat You need to ensure that users can evaluate Microsoft Teams while maintaining PSTN calling by using the Skype for Business client. Which coexistence mode should you use? 

Answer options:

A. Islands
B. Skype for Business with Teams collaboration
C. Skype for Business only
D. Meetings First

D

Reference: https://docs.microsoft.com/en-us/microsoftteams/teams-and-skypeforbusiness-coexistence-and-interoperability