Regarding Vedic history of India, consider the following statements:
1. In Rigveda, hymns are called as Suktas which means well said.
2. Some of the hymns in the Rigveda are in the form of dialogues between a sage named Vishvamitra, and two rivers, Beas and Yamuna.
3. Iron was unknown in Later Vedic period.
4. Dasyus were the opponents of Aryans who did not perform sacrifices.
Which of the statements given above are correct?