The packet sent by a node to the source to inform it of congestion is called:

Correct option is C

When a network experiences congestion, it is essential to notify the source so that it can reduce its transmission rate. The choke packet is a control packet sent by a congested node to the source node, signaling that congestion has occurred. This mechanism is part of congestion control strategies used in computer networks to avoid packet loss, delays and overall degradation in performance. Hence, the correct term for this special packet is a choke packet.
Information Booster:
1. Choke Packet:
· A control message used in congestion control.
· Sent by an intermediate node or router to the source to signal congestion in the network.
· Helps the sender slow down the data rate temporarily.
Additional Knowledge:
· Explicit: Not a specific type of control packet. May refer to Explicit Congestion Notification (ECN), but not the actual packet name in this context.
· Backpressure: A congestion control technique used in virtual circuits, where the congested node stops forwarding packets until the issue is resolved. Not a type of packet.
· Retransmission: Refers to sending the same packet again after packet loss or acknowledgment failure. Not used for congestion signaling.