What is the PDU at Layer 3 called? A. Data B. Segment C. Packet D. Frame E. Bit Solution C is correct. Packet is the PDU at the Network layer. A, B, D, and E are incorrect. A is incorrect because the data is the PDU for the top three layers. B is incorrect because the Layer 4 PDU is called a segment. D is incorrect because the frame is the PDU for the Data Link layer. E is incorrect because the bit is the PDU for the Physical layer..