gcloud compute ssh ensures that the user's public SSH key is present in the project's metadata. If the user does not have a public SSH key, one is generated using ssh-keygen and added to the project's metadata. This is similar to the other option where we copy the key explicitly to the project's metadata but here it is done automatically for us. There are also security benefits with this approach. When we use gcloud compute ssh to connect to Linux instances, we are adding a layer of security by storing your host keys as guest attributes.
Storing SSH host keys as guest attributes improve the security of your connections by helping to protect against vulnerabilities such as man-in-the-middle (MITM) attacks. On the initial boot of a VM instance, if guest attributes are enabled, Compute Engine stores your generated host keys as guest attributes.
Compute Engine then uses these host keys that were stored during the initial boot to verify all subsequent connections to the VM instance.
Ref: https://cloud.google.com/compute/docs/instances/connecting-to-instance Ref: https://cloud.google.com/sdk/gcloud/reference/compute/ssh

An external HTTP(S) load balancer is a Google-recommended solution for distributing web traffic across multiple regions and zones, and providing high availability, scalability, and security for web applications. It supports both IPv4 and IPv6 addresses, and can handle SSL/TLS termination and encryption. It also integrates with Cloud CDN, Cloud Armor, and Cloud Identity-Aware Proxy for enhanced performance and protection.
A managed instance group (MIG) can be used as a backend service for the HTTP(S) load balancer, and can automatically scale the number of VM instances based on the CPU load. A Cloud Storage bucket can also be used as a backend service for the HTTP(S) load balancer, and can serve static content such as images, videos, or HTML files. A URL map can be used to route requests to different backend services based on the path or host of the request. For example, a URL map can send requests for /static/* to the Cloud Storage bucket, and requests for /dynamic/* to the MIG. A managed SSL certificate can be used to secure the connection between the clients and the load balancer, and can be automatically provisioned and renewed by Google.
A is incorrect because an internal HTTP(S) load balancer is only visible within a VPC network, and not to the public internet. It is used for internal applications that need to communicate with other internal services.
Identity-Aware Proxy is a service that provides secure access to web applications without using a VPN. It is not a load balancer, and it does not distribute user traffic.
B is incorrect because installing HTTPS certificates on the instance is not necessary, as the HTTP(S) load balancer can handle SSL/TLS termination and encryption. It is also more complex and less secure to manage the certificates on the instance level, as they need to be updated and synchronized across multiple instances.
D is incorrect because an external network load balancer is a TCP/UDP load balancer that operates at the network layer. It is not suitable for web applications that use HTTP(S) protocols, as it does not support SSL
/TLS termination and encryption, URL maps, or Cloud Storage backends. It is also less efficient and scalable to forward the requests to the Cloud Storage from the web servers, as it adds an extra hop and latency.
:
HTTP(S) Load Balancing documentation
Setting up HTTP(S) Load Balancing with Cloud Storage
Creating and using SSL certificates
Choosing a load balancer

Coldline Storage is the perfect service to store audit logs from all the projects and is very cost-efficient as well. Coldline Storage is a very low-cost, highly durable storage service for storing infrequently accessed data.