You are writing a Compute Engine hosted application in project A that needs to securely authenticate to a Cloud Pub/Sub topic in project
B. What should you do? 

Answer options:

A. Configure the instances with a service account owned by project
B. Add the service account as a Cloud Pub/Sub publisher to project A.
B. Configure the instances with a service account owned by project A. Add the service account as a publisher on the topic.
C. Configure Application Default Credentials to use the private key of a service account owned by project
B. Add the service account as a Cloud Pub/Sub publisher to project A.
D. Configure Application Default Credentials to use the private key of a service account owned by project A. Add the service account as a publisher on the topic

B