Option 3 is the correct answer. If you want to increase the persistent disk space, resize the disk and resize the single file system instead of repartitioning and formatting the disk. Adding a persistent disk volume size to suit your performance needs does not immediately take advantage of the additional space. After that, you will need to extend the file system on disk.
Resizing the disk may require resizing the file system and partitions.
Boot disk: For VMs that use public images, resizing the VM's boot disk and restarting the VM automatically resizes the root partition and file system. If you are using an image that does not support this feature, you will need to manually resize the root partition and file system.
Non-boot disk: When you resize the disk, you need to expand the file system on the disk to use the added space.
Option 1 is incorrect. This is the response when a new disc is attached. After creating a new disk and attaching it to the VM, you need to format and mount the disk. This will allow the operating system to use the storage capacity.
Option 2 is incorrect. If you want to increase the persistent disk space, resize the disk and resize a single file system instead of repartitioning and formatting the disk.
Option 4 is incorrect. The gcloud disk resize command is not a valid command. for example, If you are using ext4, Use the resize2fs command to extend the file system.