Which type of authentication flow should you recommend for the planned integration with Office 365?

Which type of authentication flow should you recommend for the planned integration with Office 365?
A . device code
B . implicit grant
C . authorization code
D . client credentials

Answer: C

Explanation:

To use Microsoft Graph to read and write resources on behalf of a user, your app must get an access token from the Microsoft identity platform and attach the token to requests that it sends to Microsoft Graph.

One common flow used by native and mobile apps and also by some Web apps is the OAuth 2.0 authorization code grant flow.

Scenario: Email the generated invoices to customers on behalf of the current signed-in user. Any emails generated by the system will contain the invoiced.

Use Azure AD to manage identities, authentication, and authorization.

Reference: https://docs.microsoft.com/en-us/graph/auth-v2-user