What PDU format is received from the network medium by a network interface card (NIC) of a host?

The correct choice is frame because a network interface card (NIC) operates at the Data Link layer (Layer 2) of the OSI model, which is responsible for handling frames. When data is transmitted over a network, it is encapsulated into frames that include not only the payload (the actual data being sent) but also headers and trailers that contain the necessary control information such as source and destination MAC addresses.

The PDU (Protocol Data Unit) format relevant to the Data Link layer is specifically known as a frame, distinguishing it from other formats used in different layers. For instance, at Layer 3 (the Network layer), the encapsulated PDU would be called a packet, and at Layer 4 (the Transport layer), it would be referred to as a segment. The choice of the term "data" is more generalized and does not represent a specific PDU format. Thus, when considering what the NIC receives directly from the physical network medium, the appropriate term is frame.