This question is based on Assignment $1$ Quiz$/$Assignment Guide $($Task $2)$: Researching the STEPS OF NETWORKING COMMUNICATIONS: Which definition is incorrect about Protocol Data Unit $($PDU$)$ names at different layers in the TCPIIP suite:

Segment $-$ Transport Layer PDU

Packet $-$ Application Layer PDU

Frame $-$ Network Access Layer PDU

Bits $-$ A PDU used when physically transmitting data over the medium