Option 1: Krishna -> The dam has "Krishna" in its name, but this refers to Maharaja Krishna Raja Wadiyar IV, not the Krishna River.
Option 2: Kaveri -> The KRS Dam is built across the Kaveri River near Mysore, Karnataka.
Option 3: Godavari -> This river flows through central India; the dam is not on this river.
Option 4: Tungabhadra -> This is a tributary of Krishna River; the KRS Dam is not built on it.
Hence, Option 2: Kaveri -> The Krishna Raja Sagar Dam is built on the Kaveri River near Mysore. Despite having "Krishna" in its name, the dam is named after Maharaja Krishna Raja Wadiyar IV of Mysore, not the Krishna River. It was completed in 1931 and is a major source of water for irrigation and drinking purposes in Karnataka -> correct