A Linux system is getting an error indicating the root filesystem is full. Which of the following commands should be used by the systems administrator to resolve this issue? (Choose three.)

`df -h /` is the initial command to check the disk space usage of the root filesystem, providing a human-readable overview of consumed and available space.

`fdisk -l /dev/sdb` lists partition tables on `/dev/sdb`, which is for inspection, not for resolving a full root filesystem.

If the physical disk has been logically expanded (e.g., in a virtual machine), `growpart` is used to extend the underlying disk partition that contains the LVM Physical Volume, making the newly available space usable for LVM.

`pvcreate /dev/sdb` creates a Physical Volume on a new disk, which is a preparatory step for adding new storage, not for extending an existing full filesystem directly.

`lvresize -L +10G -r /dev/mapper/rootvg-rootlv` extends the `rootlv` Logical Volume by 10 gigabytes, and the crucial `-r` option automatically resizes the filesystem on that logical volume to fill the newly available space, directly addressing the 'filesystem full' issue.

`lsblk /dev/sda` lists block devices on `/dev/sda`, serving as an inspection tool rather than a solution for a full filesystem.

`parted -l /dev/mapper/rootvg-rootlv` is used to display partition tables and is not suitable for resizing an LVM logical volume.

`vgextend /dev/rootvg /dev/sdb` adds a Physical Volume (`/dev/sdb`) to a Volume Group (`/dev/rootvg`), which increases the VG's capacity but does not directly extend a Logical Volume or its filesystem.