What is the Google-recommended way for your application to authenticate to the required Google Cloud services?

Your company pushes batches of sensitive transaction data from its application server VMs to Cloud Pub/Sub for processing and storage .

What is the Google-recommended way for your application to authenticate to the required Google Cloud services?
A . Ensure that VM service accounts are granted the appropriate Cloud Pub/Sub IAM roles.
B . Ensure that VM service accounts do not have access to Cloud Pub/Sub, and use VM access scopes to
grant the appropriate Cloud Pub/Sub IAM roles.
C . Generate an OAuth2 access token for accessing Cloud Pub/Sub, encrypt it, and store it
in Cloud Storage for access from each V
E . Create a gateway to Cloud Pub/Sub using a Cloud Function, and grant the Cloud Function service account the appropriate Cloud Pub/Sub IAM roles.

Answer: A