A transmitter sends 10 PDUs using Selective Repeat with transmission window and receiving window sizes equar to 6 Pou starting the numesaines from 1. After transmitting PDUs 1.7 (PDU 7 included), the transmitter receives ACK 5 (cumulatve semantics) What can be astumes about hou ch? (a) for sure, it has not yet been received (b) it must be retransmitted because it has not been stored in the recelver buffer (c) we cannot yet know whether it has already been recelved or not (d) it must not be retransmitted because it has surely been stored in the receiver buffer If a station using the 802.11 standard receives a frame from the Access Point with errored parity bits: (a) discards the frame and sends a NACK to the AP (b) discards the frame and starts a NAV to delay access to the channel (c) discards the frame and does not send any ACK to the AP (d) discards the frame and asks the AP to retransmit the frame by sending an RTS frame A host must send a file of 3000 bytes using PDU composed by a 700 byte SDU and a 100 byte PCl over a 1 Moss channet What is the vasumision time of the last PDU sent by the host? (a) 1.2ms (b) 0.3ms (c) 6.4ms (d) 2.4ms