Integrating Cloud Pub/Sub with App Engine

A.

The correct answer is A: Enable the Cloud Pub/Sub API in the API Library on the GCP Console.

To send and consume Cloud Pub/Sub messages from your App Engine application, you need to have the Cloud Pub/Sub API enabled. However, according to the question, the API is currently disabled. Therefore, you need to enable it manually.

The Cloud Pub/Sub API can be enabled in the API Library on the GCP Console. The API Library contains all the APIs that are available on GCP, and you can enable or disable them as needed. To enable the Cloud Pub/Sub API, you can follow these steps:

1. Go to the GCP Console (console.cloud.google.com).
2. Click on the Navigation menu in the upper-left corner of the screen.
3. Expand the APIs & Services menu and click on the Library option.
4. Search for "Cloud Pub/Sub" in the search bar.
5. Click on the Cloud Pub/Sub API from the list of APIs that appear.
6. Click the Enable button to enable the API.

Once the Cloud Pub/Sub API is enabled, you can use a service account to authenticate your application to the API. Service accounts are used to authenticate applications running on GCP, and they can be granted permissions to access specific GCP resources, such as Cloud Pub/Sub.

To authenticate your App Engine application to the Cloud Pub/Sub API, you can create a service account and grant it the necessary permissions to access the API. You can then use the service account credentials to authenticate your application to the API.

In summary, to make sure your App Engine application can use Cloud Pub/Sub, you need to enable the Cloud Pub/Sub API in the API Library on the GCP Console and create a service account to authenticate your application to the API.