Option D is not correct. When you click the RDP button, you are asked to install a client or use the Windows RDP client if you are running Windows. There is no option to enter credentials or get an RDP session through the web interface.
Option B is correct. Using the internal IP address is always preferred to going through the Internet using the Public one.
Through Internal IP option:
- Chrome Remote Desktop is a service that lets you remotely access another computer by using a web browser.
- Chrome Remote Desktop works on Windows, macOS, and Linux and does not require the VM instance to have a public IP address.
Before you connect by using Chrome Remote Desktop, make sure that the following prerequisites are met:
- You've created a Windows account and password on the VM instance.
- You've installed the Chrome Remote Desktop service on the VM instance.
https://cloud.google.com/compute/docs/instances/connecting-to-windows#chrome-remote- desktop

You have to set load balancer as internal otherwise it will get exposed on public internet.

Before you begin:
1. In the Cloud Console, on the project selector page, select or create a Cloud project.
2. Make sure that billing is enabled for your Google Cloud project. Learn how to confirm billing is enabled for your project.
To use the gcloud command-line tool for this quickstart, you must first install and initialize the Cloud SDK:
1. Download and install the Cloud SDK using the instructions given on Installing Google Cloud SDK.
2. Initialize the SDK using the instructions given on Initializing Cloud SDK.
To use gcloud in Cloud Shell for this quickstart, first activate Cloud Shell using the instructions given on Starting Cloud Shell.
https://cloud.google.com/ai-platform/deep-learning-vm/docs/quickstart-cli#before-you-begin