Which type of authorization flow should you use?

You need to develop a server-based web app that will be registered with the Microsoft identity platform. The solution must ensure that the app can perform operations on behalf of the user.
Which type of authorization flow should you use?
A. authorization code
B. refresh token
C. resource owner password
D. device code

Correct Answer: A
Explanation/Reference:
Explanation:
In web server apps, the sign-in authentication flow takes these high-level steps:

You can ensure the user’s identity by validating the ID token with a public signing key that is received from the Microsoft identity platform endpoint. A session cookie is set, which can be used to identify the user on subsequent page requests.
In addition to simple sign-in, a web server app might need to access another web service, such as a REST API. In this case, the web server app engages in a combined OpenID Connect and OAuth 2.0 flow, by using the OAuth 2.0 authorization code flow.
Reference: https://docs.microsoft.com/en-us/azure/active-directory/develop/v2-app-types