Which one of the following rivers thrice forks into two streams and reunites a few miles farther on, thus forming the islands of Srirangappattanam, Sivasamudram and Srirangam?

1. The question describes a river that repeatedly divides into two streams and rejoins, forming specific islands. 2. The three islands mentioned are Srirangappattanam, Sivasamudram, and Srirangam. 3. These three river islands are formed by the Cauvery river as it flows through Karnataka and Tamil Nadu. 4. Srirangappattanam and Sivasamudram are in Karnataka, while Srirangam is near Tiruchirappalli in Tamil Nadu.