What is required for the Teams app to send a proactive message to the users?

You are developing a Microsoft Teams app that will use an Azure function to send scheduled messages from a bot to users.

What is required for the Teams app to send a proactive message to the users?
A . The bot must be approved in Azure Active Directory (Azure AD).
B . The bot must be granted admin access to the users.
C . The Teams app must be added for each user.
D . The users must send at least one message to the bot.

Answer: D

Explanation:

A proactive message is any message sent by a bot that isn’t in response to a request from a user. Sending a proactive message is different from sending a regular message. There’s no active turnContext to use for a reply. You must create the conversation before sending the message.

Reference: https://docs.microsoft.com/en-us/microsoftteams/platform/bots/how-to/conversations/send-proactive-messages