Tansen, a prominent musician in the court of Emperor Akbar, possessed a unique talent for singing that had profound effects on the environment and living beings around him. When he started singing Raag Deepak, several extraordinary phenomena occurred simultaneously.

River water started boiling:
When Tansen began to sing Raag Deepak, the river water near him started boiling. It is believed that the intense heat generated by the power of his music caused the water to heat up and eventually reach its boiling point. This phenomenon showcases the immense impact Tansen's singing had on the environment, as it could even alter the physical properties of water.

Birds became lifeless:
Another remarkable occurrence when Tansen sang Raag Deepak was that birds in the vicinity became lifeless. The powerful vibrations and frequencies emitted by his voice affected the delicate nervous systems of the birds, rendering them temporarily motionless or lifeless. This demonstrates the profound influence of Tansen's music not only on non-living elements but also on living creatures.

Leaves on the trees dried:
As Tansen's voice resonated in Raag Deepak, the leaves on the nearby trees started drying up. The intense heat generated by the music seemingly absorbed the moisture from the leaves, causing them to wither and dry. This further emphasizes the extraordinary nature of Tansen's singing and its ability to manipulate the environment.

All of the above:
Therefore, the correct answer to what happened when Tansen started singing Raag Deepak is option 'D' - all of the above. Tansen's music had the power to boil river water, render birds lifeless, and dry up the leaves on trees, showcasing the remarkable and transformative nature of his singing.

In summary:
- Tansen's singing of Raag Deepak had profound effects on the environment and living beings around him.
- The river water near him started boiling due to the intense heat generated by his music.
- Birds in the vicinity became lifeless as the vibrations and frequencies affected their nervous systems.
- The leaves on nearby trees dried up as the music absorbed moisture from them.
- All of these phenomena demonstrate the extraordinary nature of Tansen's singing and its ability to manipulate the environment.