Option 1 states that there are about 300 non-Indo-European words in Rig Veda. This means that there are words in Rig Veda that do not belong to the Indo-European language family. It implies that the vocabulary of Rig Veda includes words from other languages.
Option 2 mentions that there is a reference to dasarajna, which is the battle of ten kings, in the Rig Veda. This implies that there is a mention of this significant battle in the Rig Veda.
Option 3 states that the Rig Veda mentions that the Bharata chief Sudas fought against a confederacy of ten tribes. This suggests that the Rig Veda contains information about Sudas` involvement in a battle against a group of ten tribes.
Option 4 claims that the Purus sided with Bharata in the battle of ten kings. However, this is not true. The Rig Veda does not state that the Purus supported Bharata in this battle.
Therefore, the correct answer is option 4. However, it should be noted that the provided answer is incorrect. The correct answer should be "Alert - correct answer should be option 3. It is mentioned in the Rig Veda that the Bharata chief Sudas fought against a