What does TCP do if the sending source detects network congestion on the path to the destination?

Question:
What does TCP do if the sending source detects network congestion on the path to the destination?

• The source host will send a request for more frequent acknowledgments to the destination.
• The source will decrease the amount of data that it sends before it must receive acknowledgements from the destination.
• The destination will request retransmission of the entire message.
• The source will acknowledge the last segment that is sent and include a request for a smaller window size in the message.

Explanation: If the source determines that TCP segments are either not being acknowledged or not acknowledged in a timely manner, then it can reduce the number of bytes it sends before receiving an acknowledgment. Notice that it is the source that is reducing the number of unacknowledged bytes it sends. This does not involve changing the window size in the segment header.

Exam with this question: CCNA 1 (v5.1 + v6.0) Chapter 9 Exam Answers