Which of the following is an M.2 drive device name?

sr0 is the Linux device name assigned to optical disc drives such as CD-ROM or DVD-ROM devices, not to any type of solid-state or hard disk storage.

hda is the legacy device name for the first IDE (PATA) hard drive and has not been used for modern storage devices including M.2 drives.

The device name nvme0n1 follows the NVMe naming convention: 'nvme' identifies the driver, '0' is the controller index, and 'n1' refers to namespace 1. M.2 slots that use the PCIe-based NVMe protocol are enumerated this way by the kernel's NVMe driver. SATA-based M.2 drives are the exception and still appear as 'sd' devices because they use the AHCI controller path.

sda is the device name for the first SCSI or SATA block device; while SATA-based M.2 drives use this scheme, NVMe-based M.2 drives use the nvme naming convention instead.