TCP congestion window

The following figure shows the dynamics of a TCP congestion window 45 40 35 30 3 25- 15 S 10- 0 0 2 4 6 8 10 12 14 16 18 20 22 24 26 Transmission round i) What is the initial threshold? ii) What happened at the 6h transmission round that caused the congestion window to change from exponential growth to linear growth? iii) What kind of loss occurred at the 16th transmission round that caused the congestion window to drop? iv) What is the new threshold at 17th transmission round? v) What kind of loss occurred at the 22d transmission round that caused the congestion window to drop? vi) What is the new threshold at 23rd transmission round? vii) During which transmission rounds is Slow Start shown? Mention all viii) During which transmission rounds is Congestion Avoidance shown? Mention all