How should the application authenticate to the Google Drive API?

You are creating an App Engine application that writes a file to any user’s Google Drive.

How should the application authenticate to the Google Drive API?
A . With an OAuth Client ID that uses the https://www.googleapis.com/auth/drive.file scope to obtain an access token for each user.
B . With an OAuth Client ID with delegated domain-wide authority.
C . With the App Engine service account and https://www.googleapis.com/auth/drive.file scope that generates a signed JW
E . With the App Engine service account with delegated domain-wide authority.

Answer: B

Explanation:

Reference: https://developers.google.com/drive/api/v3/about-auth