Ssthresh Plus Three

A TCP Reno sender has SMSS = 1460, cwnd = 20 segments, and 20 segments in flight. The third duplicate ACK arrives. Following RFC 5681 section 3.2, what are ssthresh and cwnd immediately after the lost segment is retransmitted?

ssthresh = 20 segments, cwnd = 10 segments

ssthresh = 10 segments, cwnd = 13 segments

ssthresh = 10 segments, cwnd = 10 segments

ssthresh = 10 segments, cwnd = 1 segment